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fix(backend): preserve custom claims when verifying JWT M2M tokens#8697

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jacekradko merged 2 commits into from
May 29, 2026
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fix(backend): preserve custom claims when verifying JWT M2M tokens #8697

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fix(backend): preserve custom claims when verifying JWT M2M tokens
jacekradko May 28, 2026
95eb4a9
update claims handling
jacekradko May 29, 2026
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5 changes: 5 additions & 0 deletions .changeset/m2m-jwt-custom-claims.md
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Open in desktop
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
---
'@clerk/backend': patch
---

Preserve custom claims when verifying JWT-format M2M tokens. `M2MToken.fromJwtPayload` previously hardcoded `claims` to `null`, so `client.m2m.verify()` (and request-level `auth()`) dropped any custom claims embedded in the token. Custom claims are now reconstructed from the verified payload by stripping only the structural claims the backend adds when minting the token (`iss`, `sub`, `exp`, `nbf`, `iat`, `jti`). User-supplied claims such as `aud` are preserved. Tokens without custom claims still return `claims: null`, consistent with the opaque-token path.
33 changes: 32 additions & 1 deletion packages/backend/src/api/__tests__/M2MTokenApi.test.ts
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Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -417,7 +417,7 @@ describe('M2MToken', () => {
});
});

async function createSignedM2MJwt(payload = mockM2MJwtPayload) {
async function createSignedM2MJwt(payload: Record<string, unknown> = mockM2MJwtPayload) {
const { data } = await signJwt(payload, signingJwks, {
algorithm: 'RS256',
header: { typ: 'JWT', kid: 'ins_2GIoQhbUpy0hX7B2cVkuTMinXoD' },
Expand DownExpand Up@@ -455,6 +455,37 @@ describe('M2MToken', () => {
expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
});

it('preserves custom claims embedded in a JWT M2M token', async () => {
const m2mApi = new M2MTokenApi(
buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
{ secretKey: 'sk_test_xxxxx', apiUrl: 'https://api.clerk.test', skipJwksCache: true },
);

server.use(
http.get(
'https://api.clerk.test/v1/jwks',
validateHeaders(() => HttpResponse.json(mockJwks)),
),
);

const jwtToken = await createSignedM2MJwt({
...mockM2MJwtPayload,
permissions: ['read:users', 'read:orders'],
role: 'service',
});
const result = await m2mApi.verify({ token: jwtToken });

// `aud` and `scopes` from the token are user-supplied custom claims and are
// preserved in `claims`; `scopes` additionally seeds the dedicated field.
expect(result.claims).toEqual({
aud: ['mch_1xxxxx', 'mch_2xxxxx'],
scopes: 'mch_1xxxxx mch_2xxxxx',
permissions: ['read:users', 'read:orders'],
role: 'service',
});
expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
});

it('throws when JWT signature cannot be verified', async () => {
const m2mApi = new M2MTokenApi(
buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
Expand Down
26 changes: 25 additions & 1 deletion packages/backend/src/api/resources/M2MToken.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -12,6 +12,30 @@ type M2MJwtPayload = {
[key: string]: unknown;
};

// Structural claims that Clerk's machine-token service always adds when it mints
// an M2M JWT. These are mapped onto dedicated `M2MToken` fields, so they are
// stripped from `claims`. Everything else is a user-supplied custom claim and is
// surfaced through `claims`, including `aud` and `scopes`, which the backend
// treats as custom claims (they are neither reserved nor auto-added).
const M2M_RESERVED_JWT_CLAIMS = new Set(['iss', 'sub', 'exp', 'nbf', 'iat', 'jti']);

/**
* Reconstructs the custom claims that were attached at token creation by
* stripping the structural claims (see `M2M_RESERVED_JWT_CLAIMS`) from the
* verified payload. Returns `null` when no custom claims are present, matching
* the opaque-token path where a token created without claims verifies back to
* `claims: null`.
*/
function extractCustomClaims(payload: M2MJwtPayload): Record<string, any> | null {
const claims: Record<string, any> = {};
for (const key of Object.keys(payload)) {
if (!M2M_RESERVED_JWT_CLAIMS.has(key)) {
claims[key] = payload[key];
}
}
return Object.keys(claims).length > 0 ? claims : null;
}

/**
* The Backend `M2MToken` object holds information about a machine-to-machine token.
*/
Expand DownExpand Up@@ -51,7 +75,7 @@ export class M2MToken {
payload.jti ?? '', // jti should always be present in Clerk-issued M2M JWTs
payload.sub,
payload.scopes?.split(' ') ?? payload.aud ?? [],
null,
extractCustomClaims(payload),
false,
null,
payload.exp * 1000 <= Date.now() - clockSkewInMs,
Expand Down
40 changes: 39 additions & 1 deletion packages/backend/src/api/resources/__tests__/M2MToken.test.ts
View file
Open in desktop
Original file line numberDiff line numberDiff line change
Expand Up@@ -29,7 +29,9 @@ describe('M2MToken', () => {
expect(token.id).toBe('mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE');
expect(token.subject).toBe('mch_2vYVtestTESTtestTESTtestTESTtest');
expect(token.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
expect(token.claims).toBeNull();
// `aud` is a user-supplied custom claim (the backend does not auto-add it),
// so it is surfaced through `claims` while also seeding the `scopes` field.
expect(token.claims).toEqual({ aud: ['mch_1xxxxx', 'mch_2xxxxx'] });
expect(token.revoked).toBe(false);
expect(token.revocationReason).toBeNull();
expect(token.expired).toBe(false);
Expand All@@ -38,6 +40,42 @@ describe('M2MToken', () => {
expect(token.updatedAt).toBe(1666648250 * 1000);
});

it('preserves custom claims (including aud and scopes) and strips only structural claims', () => {
const payload = {
iss: 'https://clerk.m2m.example.test',
sub: 'mch_2vYVtestTESTtestTESTtestTESTtest',
aud: ['mch_1xxxxx'],
exp: 1666648550,
iat: 1666648250,
nbf: 1666648240,
jti: 'mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE',
scopes: 'scope1 scope2',
permissions: ['read:users', 'read:orders'],
role: 'service',
};

const token = M2MToken.fromJwtPayload(payload);

// `aud` and `scopes` are user-supplied custom claims in Clerk-issued M2M
// tokens (the backend neither reserves nor auto-adds them), so they are
// preserved in `claims` alongside any other custom claims.
expect(token.claims).toEqual({
aud: ['mch_1xxxxx'],
scopes: 'scope1 scope2',
permissions: ['read:users', 'read:orders'],
role: 'service',
});
// Structural claims are mapped to dedicated fields, not leaked into `claims`.
expect(token.claims).not.toHaveProperty('iss');
expect(token.claims).not.toHaveProperty('sub');
expect(token.claims).not.toHaveProperty('exp');
expect(token.claims).not.toHaveProperty('nbf');
expect(token.claims).not.toHaveProperty('iat');
expect(token.claims).not.toHaveProperty('jti');
// `scopes` is still derived onto the dedicated `scopes` field.
expect(token.scopes).toEqual(['scope1', 'scope2']);
});

it('prefers scopes claim over aud when both are present', () => {
const payload = {
sub: 'mch_test',
Expand Down
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, 'i'); if (__m === '*' || __re.test(location.href)) { // Add copy buttons to all 
 blocks
(function() {
function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
});
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codeBlock.parentElement.style.position = 'relative';
codeBlock.parentElement.appendChild(btn);
});
}
addCopyButtons();
// Re-run on dynamic content
var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
(function(){
try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
fix(backend): preserve custom claims when verifying JWT M2M tokens by jacekradko · Pull Request #8697 · clerk/javascript · GitHub
Skip to content
fix(backend): preserve custom claims when verifying JWT M2M tokens#8697

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 Merged

jacekradko
merged 2 commits into

from

May 29, 2026
 Merged


fix(backend): preserve custom claims when verifying JWT M2M tokens
#8697
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2970146

fix(backend): preserve custom claims when verifying JWT M2M tokens


jacekradko May 28, 2026
95eb4a9

update claims handling


jacekradko May 29, 2026

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5 changes: 5 additions & 0 deletions
.changeset/m2m-jwt-custom-claims.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
---
'@clerk/backend': patch
---

Preserve custom claims when verifying JWT-format M2M tokens. `M2MToken.fromJwtPayload` previously hardcoded `claims` to `null`, so `client.m2m.verify()` (and request-level `auth()`) dropped any custom claims embedded in the token. Custom claims are now reconstructed from the verified payload by stripping only the structural claims the backend adds when minting the token (`iss`, `sub`, `exp`, `nbf`, `iat`, `jti`). User-supplied claims such as `aud` are preserved. Tokens without custom claims still return `claims: null`, consistent with the opaque-token path.

33 changes: 32 additions & 1 deletion
packages/backend/src/api/__tests__/M2MTokenApi.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -417,7 +417,7 @@ describe('M2MToken', () => {
 });
 });

 async function createSignedM2MJwt(payload = mockM2MJwtPayload) {
 async function createSignedM2MJwt(payload: Record<string, unknown> = mockM2MJwtPayload) {
 const { data } = await signJwt(payload, signingJwks, {
 algorithm: 'RS256',
 header: { typ: 'JWT', kid: 'ins_2GIoQhbUpy0hX7B2cVkuTMinXoD' },
Expand DownExpand Up@@ -455,6 +455,37 @@ describe('M2MToken', () => {
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('preserves custom claims embedded in a JWT M2M token', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
 { secretKey: 'sk_test_xxxxx', apiUrl: 'https://api.clerk.test', skipJwksCache: true },
 );

 server.use(
 http.get(
 'https://api.clerk.test/v1/jwks',
 validateHeaders(() => HttpResponse.json(mockJwks)),
 ),
 );

 const jwtToken = await createSignedM2MJwt({
 ...mockM2MJwtPayload,
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 const result = await m2mApi.verify({ token: jwtToken });

 // `aud` and `scopes` from the token are user-supplied custom claims and are
 // preserved in `claims`; `scopes` additionally seeds the dedicated field.
 expect(result.claims).toEqual({
 aud: ['mch_1xxxxx', 'mch_2xxxxx'],
 scopes: 'mch_1xxxxx mch_2xxxxx',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('throws when JWT signature cannot be verified', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
Expand Down

26 changes: 25 additions & 1 deletion
packages/backend/src/api/resources/M2MToken.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -12,6 +12,30 @@ type M2MJwtPayload = {
 [key: string]: unknown;
};

// Structural claims that Clerk's machine-token service always adds when it mints
// an M2M JWT. These are mapped onto dedicated `M2MToken` fields, so they are
// stripped from `claims`. Everything else is a user-supplied custom claim and is
// surfaced through `claims`, including `aud` and `scopes`, which the backend
// treats as custom claims (they are neither reserved nor auto-added).
const M2M_RESERVED_JWT_CLAIMS = new Set(['iss', 'sub', 'exp', 'nbf', 'iat', 'jti']);

/**
 * Reconstructs the custom claims that were attached at token creation by
 * stripping the structural claims (see `M2M_RESERVED_JWT_CLAIMS`) from the
 * verified payload. Returns `null` when no custom claims are present, matching
 * the opaque-token path where a token created without claims verifies back to
 * `claims: null`.
 */
function extractCustomClaims(payload: M2MJwtPayload): Record<string, any> | null {
 const claims: Record<string, any> = {};
 for (const key of Object.keys(payload)) {
 if (!M2M_RESERVED_JWT_CLAIMS.has(key)) {
 claims[key] = payload[key];
 }
 }
 return Object.keys(claims).length > 0 ? claims : null;
}

/**
 * The Backend `M2MToken` object holds information about a machine-to-machine token.
 */
Expand DownExpand Up@@ -51,7 +75,7 @@ export class M2MToken {
 payload.jti ?? '', // jti should always be present in Clerk-issued M2M JWTs
 payload.sub,
 payload.scopes?.split(' ') ?? payload.aud ?? [],
null,
extractCustomClaims(payload),
 false,
 null,
 payload.exp * 1000 <= Date.now() - clockSkewInMs,
Expand Down

40 changes: 39 additions & 1 deletion
packages/backend/src/api/resources/__tests__/M2MToken.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -29,7 +29,9 @@ describe('M2MToken', () => {
 expect(token.id).toBe('mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE');
 expect(token.subject).toBe('mch_2vYVtestTESTtestTESTtestTESTtest');
 expect(token.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 expect(token.claims).toBeNull();
 // `aud` is a user-supplied custom claim (the backend does not auto-add it),
 // so it is surfaced through `claims` while also seeding the `scopes` field.
 expect(token.claims).toEqual({ aud: ['mch_1xxxxx', 'mch_2xxxxx'] });
 expect(token.revoked).toBe(false);
 expect(token.revocationReason).toBeNull();
 expect(token.expired).toBe(false);
Expand All@@ -38,6 +40,42 @@ describe('M2MToken', () => {
 expect(token.updatedAt).toBe(1666648250 * 1000);
 });

 it('preserves custom claims (including aud and scopes) and strips only structural claims', () => {
 const payload = {
 iss: 'https://clerk.m2m.example.test',
 sub: 'mch_2vYVtestTESTtestTESTtestTESTtest',
 aud: ['mch_1xxxxx'],
 exp: 1666648550,
 iat: 1666648250,
 nbf: 1666648240,
 jti: 'mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE',
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 };

 const token = M2MToken.fromJwtPayload(payload);

 // `aud` and `scopes` are user-supplied custom claims in Clerk-issued M2M
 // tokens (the backend neither reserves nor auto-adds them), so they are
 // preserved in `claims` alongside any other custom claims.
 expect(token.claims).toEqual({
 aud: ['mch_1xxxxx'],
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 // Structural claims are mapped to dedicated fields, not leaked into `claims`.
 expect(token.claims).not.toHaveProperty('iss');
 expect(token.claims).not.toHaveProperty('sub');
 expect(token.claims).not.toHaveProperty('exp');
 expect(token.claims).not.toHaveProperty('nbf');
 expect(token.claims).not.toHaveProperty('iat');
 expect(token.claims).not.toHaveProperty('jti');
 // `scopes` is still derived onto the dedicated `scopes` field.
 expect(token.scopes).toEqual(['scope1', 'scope2']);
 });

 it('prefers scopes claim over aud when both are present', () => {
 const payload = {
 sub: 'mch_test',
Expand Down
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var style = document.createElement('style');
style.textContent = '
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color-scheme: dark light;
}
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fix(backend): preserve custom claims when verifying JWT M2M tokens by jacekradko · Pull Request #8697 · clerk/javascript · GitHub
Skip to content
fix(backend): preserve custom claims when verifying JWT M2M tokens#8697

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 Merged

jacekradko
merged 2 commits into

from

May 29, 2026
 Merged


fix(backend): preserve custom claims when verifying JWT M2M tokens
#8697
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2970146

fix(backend): preserve custom claims when verifying JWT M2M tokens


jacekradko May 28, 2026
95eb4a9

update claims handling


jacekradko May 29, 2026

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5 changes: 5 additions & 0 deletions
.changeset/m2m-jwt-custom-claims.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
---
'@clerk/backend': patch
---

Preserve custom claims when verifying JWT-format M2M tokens. `M2MToken.fromJwtPayload` previously hardcoded `claims` to `null`, so `client.m2m.verify()` (and request-level `auth()`) dropped any custom claims embedded in the token. Custom claims are now reconstructed from the verified payload by stripping only the structural claims the backend adds when minting the token (`iss`, `sub`, `exp`, `nbf`, `iat`, `jti`). User-supplied claims such as `aud` are preserved. Tokens without custom claims still return `claims: null`, consistent with the opaque-token path.

33 changes: 32 additions & 1 deletion
packages/backend/src/api/__tests__/M2MTokenApi.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -417,7 +417,7 @@ describe('M2MToken', () => {
 });
 });

 async function createSignedM2MJwt(payload = mockM2MJwtPayload) {
 async function createSignedM2MJwt(payload: Record<string, unknown> = mockM2MJwtPayload) {
 const { data } = await signJwt(payload, signingJwks, {
 algorithm: 'RS256',
 header: { typ: 'JWT', kid: 'ins_2GIoQhbUpy0hX7B2cVkuTMinXoD' },
Expand DownExpand Up@@ -455,6 +455,37 @@ describe('M2MToken', () => {
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('preserves custom claims embedded in a JWT M2M token', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
 { secretKey: 'sk_test_xxxxx', apiUrl: 'https://api.clerk.test', skipJwksCache: true },
 );

 server.use(
 http.get(
 'https://api.clerk.test/v1/jwks',
 validateHeaders(() => HttpResponse.json(mockJwks)),
 ),
 );

 const jwtToken = await createSignedM2MJwt({
 ...mockM2MJwtPayload,
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 const result = await m2mApi.verify({ token: jwtToken });

 // `aud` and `scopes` from the token are user-supplied custom claims and are
 // preserved in `claims`; `scopes` additionally seeds the dedicated field.
 expect(result.claims).toEqual({
 aud: ['mch_1xxxxx', 'mch_2xxxxx'],
 scopes: 'mch_1xxxxx mch_2xxxxx',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('throws when JWT signature cannot be verified', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
Expand Down

26 changes: 25 additions & 1 deletion
packages/backend/src/api/resources/M2MToken.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -12,6 +12,30 @@ type M2MJwtPayload = {
 [key: string]: unknown;
};

// Structural claims that Clerk's machine-token service always adds when it mints
// an M2M JWT. These are mapped onto dedicated `M2MToken` fields, so they are
// stripped from `claims`. Everything else is a user-supplied custom claim and is
// surfaced through `claims`, including `aud` and `scopes`, which the backend
// treats as custom claims (they are neither reserved nor auto-added).
const M2M_RESERVED_JWT_CLAIMS = new Set(['iss', 'sub', 'exp', 'nbf', 'iat', 'jti']);

/**
 * Reconstructs the custom claims that were attached at token creation by
 * stripping the structural claims (see `M2M_RESERVED_JWT_CLAIMS`) from the
 * verified payload. Returns `null` when no custom claims are present, matching
 * the opaque-token path where a token created without claims verifies back to
 * `claims: null`.
 */
function extractCustomClaims(payload: M2MJwtPayload): Record<string, any> | null {
 const claims: Record<string, any> = {};
 for (const key of Object.keys(payload)) {
 if (!M2M_RESERVED_JWT_CLAIMS.has(key)) {
 claims[key] = payload[key];
 }
 }
 return Object.keys(claims).length > 0 ? claims : null;
}

/**
 * The Backend `M2MToken` object holds information about a machine-to-machine token.
 */
Expand DownExpand Up@@ -51,7 +75,7 @@ export class M2MToken {
 payload.jti ?? '', // jti should always be present in Clerk-issued M2M JWTs
 payload.sub,
 payload.scopes?.split(' ') ?? payload.aud ?? [],
null,
extractCustomClaims(payload),
 false,
 null,
 payload.exp * 1000 <= Date.now() - clockSkewInMs,
Expand Down

40 changes: 39 additions & 1 deletion
packages/backend/src/api/resources/__tests__/M2MToken.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -29,7 +29,9 @@ describe('M2MToken', () => {
 expect(token.id).toBe('mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE');
 expect(token.subject).toBe('mch_2vYVtestTESTtestTESTtestTESTtest');
 expect(token.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 expect(token.claims).toBeNull();
 // `aud` is a user-supplied custom claim (the backend does not auto-add it),
 // so it is surfaced through `claims` while also seeding the `scopes` field.
 expect(token.claims).toEqual({ aud: ['mch_1xxxxx', 'mch_2xxxxx'] });
 expect(token.revoked).toBe(false);
 expect(token.revocationReason).toBeNull();
 expect(token.expired).toBe(false);
Expand All@@ -38,6 +40,42 @@ describe('M2MToken', () => {
 expect(token.updatedAt).toBe(1666648250 * 1000);
 });

 it('preserves custom claims (including aud and scopes) and strips only structural claims', () => {
 const payload = {
 iss: 'https://clerk.m2m.example.test',
 sub: 'mch_2vYVtestTESTtestTESTtestTESTtest',
 aud: ['mch_1xxxxx'],
 exp: 1666648550,
 iat: 1666648250,
 nbf: 1666648240,
 jti: 'mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE',
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 };

 const token = M2MToken.fromJwtPayload(payload);

 // `aud` and `scopes` are user-supplied custom claims in Clerk-issued M2M
 // tokens (the backend neither reserves nor auto-adds them), so they are
 // preserved in `claims` alongside any other custom claims.
 expect(token.claims).toEqual({
 aud: ['mch_1xxxxx'],
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 // Structural claims are mapped to dedicated fields, not leaked into `claims`.
 expect(token.claims).not.toHaveProperty('iss');
 expect(token.claims).not.toHaveProperty('sub');
 expect(token.claims).not.toHaveProperty('exp');
 expect(token.claims).not.toHaveProperty('nbf');
 expect(token.claims).not.toHaveProperty('iat');
 expect(token.claims).not.toHaveProperty('jti');
 // `scopes` is still derived onto the dedicated `scopes` field.
 expect(token.scopes).toEqual(['scope1', 'scope2']);
 });

 it('prefers scopes claim over aud when both are present', () => {
 const payload = {
 sub: 'mch_test',
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Highlight search terms from Google/DuckDuckGo/Bing referrer
(function() {
var ref = document.referrer;
var terms = [];
if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {
var url = new URL(ref);
var q = url.searchParams.get('q') || url.searchParams.get('p');
if (q) {
terms = q.split(/\s+/).filter(function(t) { return t.length > 2; });
}
}
if (terms.length === 0) return;
var style = document.createElement('style');
style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';
document.head.appendChild(style);
function highlight(node) {
if (node.nodeType === 3) { // text node
var text = node.textContent;
var found = false;
terms.forEach(function(term) {
var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\]\\]/g, '\\') + ')', 'gi');
if (regex.test(text)) {
found = true;
var frag = document.createDocumentFragment();
var parts = text.split(regex);
parts.forEach(function(part, i) {
if (i % 2 === 0) {
frag.appendChild(document.createTextNode(part));
} else {
var span = document.createElement('span');
span.className = 'userscript-highlight';
span.textContent = part;
frag.appendChild(span);
}
});
node.parentNode.replaceChild(frag, node);
}
});
} else if (node.nodeType === 1 && node.childNodes) { // element
var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];
if (!skipTags.includes(node.tagName)) {
Array.from(node.childNodes).forEach(highlight);
}
}
}
highlight(document.body);
// Re-highlight on dynamic content
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1 || node.nodeType === 3) highlight(node);
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
fix(backend): preserve custom claims when verifying JWT M2M tokens by jacekradko · Pull Request #8697 · clerk/javascript · GitHub
Skip to content
fix(backend): preserve custom claims when verifying JWT M2M tokens#8697

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merged 2 commits into

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May 29, 2026
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fix(backend): preserve custom claims when verifying JWT M2M tokens
#8697
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2970146

fix(backend): preserve custom claims when verifying JWT M2M tokens


jacekradko May 28, 2026
95eb4a9

update claims handling


jacekradko May 29, 2026

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5 changes: 5 additions & 0 deletions
.changeset/m2m-jwt-custom-claims.md

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Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
---
'@clerk/backend': patch
---

Preserve custom claims when verifying JWT-format M2M tokens. `M2MToken.fromJwtPayload` previously hardcoded `claims` to `null`, so `client.m2m.verify()` (and request-level `auth()`) dropped any custom claims embedded in the token. Custom claims are now reconstructed from the verified payload by stripping only the structural claims the backend adds when minting the token (`iss`, `sub`, `exp`, `nbf`, `iat`, `jti`). User-supplied claims such as `aud` are preserved. Tokens without custom claims still return `claims: null`, consistent with the opaque-token path.

33 changes: 32 additions & 1 deletion
packages/backend/src/api/__tests__/M2MTokenApi.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -417,7 +417,7 @@ describe('M2MToken', () => {
 });
 });

 async function createSignedM2MJwt(payload = mockM2MJwtPayload) {
 async function createSignedM2MJwt(payload: Record<string, unknown> = mockM2MJwtPayload) {
 const { data } = await signJwt(payload, signingJwks, {
 algorithm: 'RS256',
 header: { typ: 'JWT', kid: 'ins_2GIoQhbUpy0hX7B2cVkuTMinXoD' },
Expand DownExpand Up@@ -455,6 +455,37 @@ describe('M2MToken', () => {
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('preserves custom claims embedded in a JWT M2M token', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
 { secretKey: 'sk_test_xxxxx', apiUrl: 'https://api.clerk.test', skipJwksCache: true },
 );

 server.use(
 http.get(
 'https://api.clerk.test/v1/jwks',
 validateHeaders(() => HttpResponse.json(mockJwks)),
 ),
 );

 const jwtToken = await createSignedM2MJwt({
 ...mockM2MJwtPayload,
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 const result = await m2mApi.verify({ token: jwtToken });

 // `aud` and `scopes` from the token are user-supplied custom claims and are
 // preserved in `claims`; `scopes` additionally seeds the dedicated field.
 expect(result.claims).toEqual({
 aud: ['mch_1xxxxx', 'mch_2xxxxx'],
 scopes: 'mch_1xxxxx mch_2xxxxx',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('throws when JWT signature cannot be verified', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
Expand Down

26 changes: 25 additions & 1 deletion
packages/backend/src/api/resources/M2MToken.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -12,6 +12,30 @@ type M2MJwtPayload = {
 [key: string]: unknown;
};

// Structural claims that Clerk's machine-token service always adds when it mints
// an M2M JWT. These are mapped onto dedicated `M2MToken` fields, so they are
// stripped from `claims`. Everything else is a user-supplied custom claim and is
// surfaced through `claims`, including `aud` and `scopes`, which the backend
// treats as custom claims (they are neither reserved nor auto-added).
const M2M_RESERVED_JWT_CLAIMS = new Set(['iss', 'sub', 'exp', 'nbf', 'iat', 'jti']);

/**
 * Reconstructs the custom claims that were attached at token creation by
 * stripping the structural claims (see `M2M_RESERVED_JWT_CLAIMS`) from the
 * verified payload. Returns `null` when no custom claims are present, matching
 * the opaque-token path where a token created without claims verifies back to
 * `claims: null`.
 */
function extractCustomClaims(payload: M2MJwtPayload): Record<string, any> | null {
 const claims: Record<string, any> = {};
 for (const key of Object.keys(payload)) {
 if (!M2M_RESERVED_JWT_CLAIMS.has(key)) {
 claims[key] = payload[key];
 }
 }
 return Object.keys(claims).length > 0 ? claims : null;
}

/**
 * The Backend `M2MToken` object holds information about a machine-to-machine token.
 */
Expand DownExpand Up@@ -51,7 +75,7 @@ export class M2MToken {
 payload.jti ?? '', // jti should always be present in Clerk-issued M2M JWTs
 payload.sub,
 payload.scopes?.split(' ') ?? payload.aud ?? [],
null,
extractCustomClaims(payload),
 false,
 null,
 payload.exp * 1000 <= Date.now() - clockSkewInMs,
Expand Down

40 changes: 39 additions & 1 deletion
packages/backend/src/api/resources/__tests__/M2MToken.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -29,7 +29,9 @@ describe('M2MToken', () => {
 expect(token.id).toBe('mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE');
 expect(token.subject).toBe('mch_2vYVtestTESTtestTESTtestTESTtest');
 expect(token.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 expect(token.claims).toBeNull();
 // `aud` is a user-supplied custom claim (the backend does not auto-add it),
 // so it is surfaced through `claims` while also seeding the `scopes` field.
 expect(token.claims).toEqual({ aud: ['mch_1xxxxx', 'mch_2xxxxx'] });
 expect(token.revoked).toBe(false);
 expect(token.revocationReason).toBeNull();
 expect(token.expired).toBe(false);
Expand All@@ -38,6 +40,42 @@ describe('M2MToken', () => {
 expect(token.updatedAt).toBe(1666648250 * 1000);
 });

 it('preserves custom claims (including aud and scopes) and strips only structural claims', () => {
 const payload = {
 iss: 'https://clerk.m2m.example.test',
 sub: 'mch_2vYVtestTESTtestTESTtestTESTtest',
 aud: ['mch_1xxxxx'],
 exp: 1666648550,
 iat: 1666648250,
 nbf: 1666648240,
 jti: 'mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE',
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 };

 const token = M2MToken.fromJwtPayload(payload);

 // `aud` and `scopes` are user-supplied custom claims in Clerk-issued M2M
 // tokens (the backend neither reserves nor auto-adds them), so they are
 // preserved in `claims` alongside any other custom claims.
 expect(token.claims).toEqual({
 aud: ['mch_1xxxxx'],
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 // Structural claims are mapped to dedicated fields, not leaked into `claims`.
 expect(token.claims).not.toHaveProperty('iss');
 expect(token.claims).not.toHaveProperty('sub');
 expect(token.claims).not.toHaveProperty('exp');
 expect(token.claims).not.toHaveProperty('nbf');
 expect(token.claims).not.toHaveProperty('iat');
 expect(token.claims).not.toHaveProperty('jti');
 // `scopes` is still derived onto the dedicated `scopes` field.
 expect(token.scopes).toEqual(['scope1', 'scope2']);
 });

 it('prefers scopes claim over aud when both are present', () => {
 const payload = {
 sub: 'mch_test',
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
fix(backend): preserve custom claims when verifying JWT M2M tokens by jacekradko · Pull Request #8697 · clerk/javascript · GitHub
Skip to content
fix(backend): preserve custom claims when verifying JWT M2M tokens#8697

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 Merged

jacekradko
merged 2 commits into

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May 29, 2026
 Merged


fix(backend): preserve custom claims when verifying JWT M2M tokens
#8697
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2970146

fix(backend): preserve custom claims when verifying JWT M2M tokens


jacekradko May 28, 2026
95eb4a9

update claims handling


jacekradko May 29, 2026

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5 changes: 5 additions & 0 deletions
.changeset/m2m-jwt-custom-claims.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
---
'@clerk/backend': patch
---

Preserve custom claims when verifying JWT-format M2M tokens. `M2MToken.fromJwtPayload` previously hardcoded `claims` to `null`, so `client.m2m.verify()` (and request-level `auth()`) dropped any custom claims embedded in the token. Custom claims are now reconstructed from the verified payload by stripping only the structural claims the backend adds when minting the token (`iss`, `sub`, `exp`, `nbf`, `iat`, `jti`). User-supplied claims such as `aud` are preserved. Tokens without custom claims still return `claims: null`, consistent with the opaque-token path.

33 changes: 32 additions & 1 deletion
packages/backend/src/api/__tests__/M2MTokenApi.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -417,7 +417,7 @@ describe('M2MToken', () => {
 });
 });

 async function createSignedM2MJwt(payload = mockM2MJwtPayload) {
 async function createSignedM2MJwt(payload: Record<string, unknown> = mockM2MJwtPayload) {
 const { data } = await signJwt(payload, signingJwks, {
 algorithm: 'RS256',
 header: { typ: 'JWT', kid: 'ins_2GIoQhbUpy0hX7B2cVkuTMinXoD' },
Expand DownExpand Up@@ -455,6 +455,37 @@ describe('M2MToken', () => {
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('preserves custom claims embedded in a JWT M2M token', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
 { secretKey: 'sk_test_xxxxx', apiUrl: 'https://api.clerk.test', skipJwksCache: true },
 );

 server.use(
 http.get(
 'https://api.clerk.test/v1/jwks',
 validateHeaders(() => HttpResponse.json(mockJwks)),
 ),
 );

 const jwtToken = await createSignedM2MJwt({
 ...mockM2MJwtPayload,
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 const result = await m2mApi.verify({ token: jwtToken });

 // `aud` and `scopes` from the token are user-supplied custom claims and are
 // preserved in `claims`; `scopes` additionally seeds the dedicated field.
 expect(result.claims).toEqual({
 aud: ['mch_1xxxxx', 'mch_2xxxxx'],
 scopes: 'mch_1xxxxx mch_2xxxxx',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('throws when JWT signature cannot be verified', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
Expand Down

26 changes: 25 additions & 1 deletion
packages/backend/src/api/resources/M2MToken.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -12,6 +12,30 @@ type M2MJwtPayload = {
 [key: string]: unknown;
};

// Structural claims that Clerk's machine-token service always adds when it mints
// an M2M JWT. These are mapped onto dedicated `M2MToken` fields, so they are
// stripped from `claims`. Everything else is a user-supplied custom claim and is
// surfaced through `claims`, including `aud` and `scopes`, which the backend
// treats as custom claims (they are neither reserved nor auto-added).
const M2M_RESERVED_JWT_CLAIMS = new Set(['iss', 'sub', 'exp', 'nbf', 'iat', 'jti']);

/**
 * Reconstructs the custom claims that were attached at token creation by
 * stripping the structural claims (see `M2M_RESERVED_JWT_CLAIMS`) from the
 * verified payload. Returns `null` when no custom claims are present, matching
 * the opaque-token path where a token created without claims verifies back to
 * `claims: null`.
 */
function extractCustomClaims(payload: M2MJwtPayload): Record<string, any> | null {
 const claims: Record<string, any> = {};
 for (const key of Object.keys(payload)) {
 if (!M2M_RESERVED_JWT_CLAIMS.has(key)) {
 claims[key] = payload[key];
 }
 }
 return Object.keys(claims).length > 0 ? claims : null;
}

/**
 * The Backend `M2MToken` object holds information about a machine-to-machine token.
 */
Expand DownExpand Up@@ -51,7 +75,7 @@ export class M2MToken {
 payload.jti ?? '', // jti should always be present in Clerk-issued M2M JWTs
 payload.sub,
 payload.scopes?.split(' ') ?? payload.aud ?? [],
null,
extractCustomClaims(payload),
 false,
 null,
 payload.exp * 1000 <= Date.now() - clockSkewInMs,
Expand Down

40 changes: 39 additions & 1 deletion
packages/backend/src/api/resources/__tests__/M2MToken.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -29,7 +29,9 @@ describe('M2MToken', () => {
 expect(token.id).toBe('mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE');
 expect(token.subject).toBe('mch_2vYVtestTESTtestTESTtestTESTtest');
 expect(token.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 expect(token.claims).toBeNull();
 // `aud` is a user-supplied custom claim (the backend does not auto-add it),
 // so it is surfaced through `claims` while also seeding the `scopes` field.
 expect(token.claims).toEqual({ aud: ['mch_1xxxxx', 'mch_2xxxxx'] });
 expect(token.revoked).toBe(false);
 expect(token.revocationReason).toBeNull();
 expect(token.expired).toBe(false);
Expand All@@ -38,6 +40,42 @@ describe('M2MToken', () => {
 expect(token.updatedAt).toBe(1666648250 * 1000);
 });

 it('preserves custom claims (including aud and scopes) and strips only structural claims', () => {
 const payload = {
 iss: 'https://clerk.m2m.example.test',
 sub: 'mch_2vYVtestTESTtestTESTtestTESTtest',
 aud: ['mch_1xxxxx'],
 exp: 1666648550,
 iat: 1666648250,
 nbf: 1666648240,
 jti: 'mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE',
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 };

 const token = M2MToken.fromJwtPayload(payload);

 // `aud` and `scopes` are user-supplied custom claims in Clerk-issued M2M
 // tokens (the backend neither reserves nor auto-adds them), so they are
 // preserved in `claims` alongside any other custom claims.
 expect(token.claims).toEqual({
 aud: ['mch_1xxxxx'],
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 // Structural claims are mapped to dedicated fields, not leaked into `claims`.
 expect(token.claims).not.toHaveProperty('iss');
 expect(token.claims).not.toHaveProperty('sub');
 expect(token.claims).not.toHaveProperty('exp');
 expect(token.claims).not.toHaveProperty('nbf');
 expect(token.claims).not.toHaveProperty('iat');
 expect(token.claims).not.toHaveProperty('jti');
 // `scopes` is still derived onto the dedicated `scopes` field.
 expect(token.scopes).toEqual(['scope1', 'scope2']);
 });

 it('prefers scopes claim over aud when both are present', () => {
 const payload = {
 sub: 'mch_test',
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
fix(backend): preserve custom claims when verifying JWT M2M tokens by jacekradko · Pull Request #8697 · clerk/javascript · GitHub
Skip to content
fix(backend): preserve custom claims when verifying JWT M2M tokens#8697

New issue

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Sign in
to your account

 Merged

jacekradko
merged 2 commits into

from

May 29, 2026
 Merged


fix(backend): preserve custom claims when verifying JWT M2M tokens
#8697
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2970146

fix(backend): preserve custom claims when verifying JWT M2M tokens


jacekradko May 28, 2026
95eb4a9

update claims handling


jacekradko May 29, 2026

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.changeset/m2m-jwt-custom-claims.md

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
---
'@clerk/backend': patch
---

Preserve custom claims when verifying JWT-format M2M tokens. `M2MToken.fromJwtPayload` previously hardcoded `claims` to `null`, so `client.m2m.verify()` (and request-level `auth()`) dropped any custom claims embedded in the token. Custom claims are now reconstructed from the verified payload by stripping only the structural claims the backend adds when minting the token (`iss`, `sub`, `exp`, `nbf`, `iat`, `jti`). User-supplied claims such as `aud` are preserved. Tokens without custom claims still return `claims: null`, consistent with the opaque-token path.

33 changes: 32 additions & 1 deletion
packages/backend/src/api/__tests__/M2MTokenApi.test.ts

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Original file line numberDiff line numberDiff line change
Expand Up@@ -417,7 +417,7 @@ describe('M2MToken', () => {
 });
 });

 async function createSignedM2MJwt(payload = mockM2MJwtPayload) {
 async function createSignedM2MJwt(payload: Record<string, unknown> = mockM2MJwtPayload) {
 const { data } = await signJwt(payload, signingJwks, {
 algorithm: 'RS256',
 header: { typ: 'JWT', kid: 'ins_2GIoQhbUpy0hX7B2cVkuTMinXoD' },
Expand DownExpand Up@@ -455,6 +455,37 @@ describe('M2MToken', () => {
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('preserves custom claims embedded in a JWT M2M token', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
 { secretKey: 'sk_test_xxxxx', apiUrl: 'https://api.clerk.test', skipJwksCache: true },
 );

 server.use(
 http.get(
 'https://api.clerk.test/v1/jwks',
 validateHeaders(() => HttpResponse.json(mockJwks)),
 ),
 );

 const jwtToken = await createSignedM2MJwt({
 ...mockM2MJwtPayload,
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 const result = await m2mApi.verify({ token: jwtToken });

 // `aud` and `scopes` from the token are user-supplied custom claims and are
 // preserved in `claims`; `scopes` additionally seeds the dedicated field.
 expect(result.claims).toEqual({
 aud: ['mch_1xxxxx', 'mch_2xxxxx'],
 scopes: 'mch_1xxxxx mch_2xxxxx',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('throws when JWT signature cannot be verified', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
Expand Down

26 changes: 25 additions & 1 deletion
packages/backend/src/api/resources/M2MToken.ts

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Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -12,6 +12,30 @@ type M2MJwtPayload = {
 [key: string]: unknown;
};

// Structural claims that Clerk's machine-token service always adds when it mints
// an M2M JWT. These are mapped onto dedicated `M2MToken` fields, so they are
// stripped from `claims`. Everything else is a user-supplied custom claim and is
// surfaced through `claims`, including `aud` and `scopes`, which the backend
// treats as custom claims (they are neither reserved nor auto-added).
const M2M_RESERVED_JWT_CLAIMS = new Set(['iss', 'sub', 'exp', 'nbf', 'iat', 'jti']);

/**
 * Reconstructs the custom claims that were attached at token creation by
 * stripping the structural claims (see `M2M_RESERVED_JWT_CLAIMS`) from the
 * verified payload. Returns `null` when no custom claims are present, matching
 * the opaque-token path where a token created without claims verifies back to
 * `claims: null`.
 */
function extractCustomClaims(payload: M2MJwtPayload): Record<string, any> | null {
 const claims: Record<string, any> = {};
 for (const key of Object.keys(payload)) {
 if (!M2M_RESERVED_JWT_CLAIMS.has(key)) {
 claims[key] = payload[key];
 }
 }
 return Object.keys(claims).length > 0 ? claims : null;
}

/**
 * The Backend `M2MToken` object holds information about a machine-to-machine token.
 */
Expand DownExpand Up@@ -51,7 +75,7 @@ export class M2MToken {
 payload.jti ?? '', // jti should always be present in Clerk-issued M2M JWTs
 payload.sub,
 payload.scopes?.split(' ') ?? payload.aud ?? [],
null,
extractCustomClaims(payload),
 false,
 null,
 payload.exp * 1000 <= Date.now() - clockSkewInMs,
Expand Down

40 changes: 39 additions & 1 deletion
packages/backend/src/api/resources/__tests__/M2MToken.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -29,7 +29,9 @@ describe('M2MToken', () => {
 expect(token.id).toBe('mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE');
 expect(token.subject).toBe('mch_2vYVtestTESTtestTESTtestTESTtest');
 expect(token.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 expect(token.claims).toBeNull();
 // `aud` is a user-supplied custom claim (the backend does not auto-add it),
 // so it is surfaced through `claims` while also seeding the `scopes` field.
 expect(token.claims).toEqual({ aud: ['mch_1xxxxx', 'mch_2xxxxx'] });
 expect(token.revoked).toBe(false);
 expect(token.revocationReason).toBeNull();
 expect(token.expired).toBe(false);
Expand All@@ -38,6 +40,42 @@ describe('M2MToken', () => {
 expect(token.updatedAt).toBe(1666648250 * 1000);
 });

 it('preserves custom claims (including aud and scopes) and strips only structural claims', () => {
 const payload = {
 iss: 'https://clerk.m2m.example.test',
 sub: 'mch_2vYVtestTESTtestTESTtestTESTtest',
 aud: ['mch_1xxxxx'],
 exp: 1666648550,
 iat: 1666648250,
 nbf: 1666648240,
 jti: 'mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE',
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 };

 const token = M2MToken.fromJwtPayload(payload);

 // `aud` and `scopes` are user-supplied custom claims in Clerk-issued M2M
 // tokens (the backend neither reserves nor auto-adds them), so they are
 // preserved in `claims` alongside any other custom claims.
 expect(token.claims).toEqual({
 aud: ['mch_1xxxxx'],
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 // Structural claims are mapped to dedicated fields, not leaked into `claims`.
 expect(token.claims).not.toHaveProperty('iss');
 expect(token.claims).not.toHaveProperty('sub');
 expect(token.claims).not.toHaveProperty('exp');
 expect(token.claims).not.toHaveProperty('nbf');
 expect(token.claims).not.toHaveProperty('iat');
 expect(token.claims).not.toHaveProperty('jti');
 // `scopes` is still derived onto the dedicated `scopes` field.
 expect(token.scopes).toEqual(['scope1', 'scope2']);
 });

 it('prefers scopes claim over aud when both are present', () => {
 const payload = {
 sub: 'mch_test',
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
});
}
unstick();
var observer = new MutationObserver(unstick);
observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
})();
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
fix(backend): preserve custom claims when verifying JWT M2M tokens by jacekradko · Pull Request #8697 · clerk/javascript · GitHub
Skip to content
fix(backend): preserve custom claims when verifying JWT M2M tokens#8697

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jacekradko
merged 2 commits into

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May 29, 2026
 Merged


fix(backend): preserve custom claims when verifying JWT M2M tokens
#8697
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2970146

fix(backend): preserve custom claims when verifying JWT M2M tokens


jacekradko May 28, 2026
95eb4a9

update claims handling


jacekradko May 29, 2026

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5 changes: 5 additions & 0 deletions
.changeset/m2m-jwt-custom-claims.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
---
'@clerk/backend': patch
---

Preserve custom claims when verifying JWT-format M2M tokens. `M2MToken.fromJwtPayload` previously hardcoded `claims` to `null`, so `client.m2m.verify()` (and request-level `auth()`) dropped any custom claims embedded in the token. Custom claims are now reconstructed from the verified payload by stripping only the structural claims the backend adds when minting the token (`iss`, `sub`, `exp`, `nbf`, `iat`, `jti`). User-supplied claims such as `aud` are preserved. Tokens without custom claims still return `claims: null`, consistent with the opaque-token path.

33 changes: 32 additions & 1 deletion
packages/backend/src/api/__tests__/M2MTokenApi.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -417,7 +417,7 @@ describe('M2MToken', () => {
 });
 });

 async function createSignedM2MJwt(payload = mockM2MJwtPayload) {
 async function createSignedM2MJwt(payload: Record<string, unknown> = mockM2MJwtPayload) {
 const { data } = await signJwt(payload, signingJwks, {
 algorithm: 'RS256',
 header: { typ: 'JWT', kid: 'ins_2GIoQhbUpy0hX7B2cVkuTMinXoD' },
Expand DownExpand Up@@ -455,6 +455,37 @@ describe('M2MToken', () => {
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('preserves custom claims embedded in a JWT M2M token', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
 { secretKey: 'sk_test_xxxxx', apiUrl: 'https://api.clerk.test', skipJwksCache: true },
 );

 server.use(
 http.get(
 'https://api.clerk.test/v1/jwks',
 validateHeaders(() => HttpResponse.json(mockJwks)),
 ),
 );

 const jwtToken = await createSignedM2MJwt({
 ...mockM2MJwtPayload,
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 const result = await m2mApi.verify({ token: jwtToken });

 // `aud` and `scopes` from the token are user-supplied custom claims and are
 // preserved in `claims`; `scopes` additionally seeds the dedicated field.
 expect(result.claims).toEqual({
 aud: ['mch_1xxxxx', 'mch_2xxxxx'],
 scopes: 'mch_1xxxxx mch_2xxxxx',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('throws when JWT signature cannot be verified', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
Expand Down

26 changes: 25 additions & 1 deletion
packages/backend/src/api/resources/M2MToken.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -12,6 +12,30 @@ type M2MJwtPayload = {
 [key: string]: unknown;
};

// Structural claims that Clerk's machine-token service always adds when it mints
// an M2M JWT. These are mapped onto dedicated `M2MToken` fields, so they are
// stripped from `claims`. Everything else is a user-supplied custom claim and is
// surfaced through `claims`, including `aud` and `scopes`, which the backend
// treats as custom claims (they are neither reserved nor auto-added).
const M2M_RESERVED_JWT_CLAIMS = new Set(['iss', 'sub', 'exp', 'nbf', 'iat', 'jti']);

/**
 * Reconstructs the custom claims that were attached at token creation by
 * stripping the structural claims (see `M2M_RESERVED_JWT_CLAIMS`) from the
 * verified payload. Returns `null` when no custom claims are present, matching
 * the opaque-token path where a token created without claims verifies back to
 * `claims: null`.
 */
function extractCustomClaims(payload: M2MJwtPayload): Record<string, any> | null {
 const claims: Record<string, any> = {};
 for (const key of Object.keys(payload)) {
 if (!M2M_RESERVED_JWT_CLAIMS.has(key)) {
 claims[key] = payload[key];
 }
 }
 return Object.keys(claims).length > 0 ? claims : null;
}

/**
 * The Backend `M2MToken` object holds information about a machine-to-machine token.
 */
Expand DownExpand Up@@ -51,7 +75,7 @@ export class M2MToken {
 payload.jti ?? '', // jti should always be present in Clerk-issued M2M JWTs
 payload.sub,
 payload.scopes?.split(' ') ?? payload.aud ?? [],
null,
extractCustomClaims(payload),
 false,
 null,
 payload.exp * 1000 <= Date.now() - clockSkewInMs,
Expand Down

40 changes: 39 additions & 1 deletion
packages/backend/src/api/resources/__tests__/M2MToken.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -29,7 +29,9 @@ describe('M2MToken', () => {
 expect(token.id).toBe('mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE');
 expect(token.subject).toBe('mch_2vYVtestTESTtestTESTtestTESTtest');
 expect(token.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 expect(token.claims).toBeNull();
 // `aud` is a user-supplied custom claim (the backend does not auto-add it),
 // so it is surfaced through `claims` while also seeding the `scopes` field.
 expect(token.claims).toEqual({ aud: ['mch_1xxxxx', 'mch_2xxxxx'] });
 expect(token.revoked).toBe(false);
 expect(token.revocationReason).toBeNull();
 expect(token.expired).toBe(false);
Expand All@@ -38,6 +40,42 @@ describe('M2MToken', () => {
 expect(token.updatedAt).toBe(1666648250 * 1000);
 });

 it('preserves custom claims (including aud and scopes) and strips only structural claims', () => {
 const payload = {
 iss: 'https://clerk.m2m.example.test',
 sub: 'mch_2vYVtestTESTtestTESTtestTESTtest',
 aud: ['mch_1xxxxx'],
 exp: 1666648550,
 iat: 1666648250,
 nbf: 1666648240,
 jti: 'mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE',
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 };

 const token = M2MToken.fromJwtPayload(payload);

 // `aud` and `scopes` are user-supplied custom claims in Clerk-issued M2M
 // tokens (the backend neither reserves nor auto-adds them), so they are
 // preserved in `claims` alongside any other custom claims.
 expect(token.claims).toEqual({
 aud: ['mch_1xxxxx'],
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 // Structural claims are mapped to dedicated fields, not leaked into `claims`.
 expect(token.claims).not.toHaveProperty('iss');
 expect(token.claims).not.toHaveProperty('sub');
 expect(token.claims).not.toHaveProperty('exp');
 expect(token.claims).not.toHaveProperty('nbf');
 expect(token.claims).not.toHaveProperty('iat');
 expect(token.claims).not.toHaveProperty('jti');
 // `scopes` is still derived onto the dedicated `scopes` field.
 expect(token.scopes).toEqual(['scope1', 'scope2']);
 });

 it('prefers scopes claim over aud when both are present', () => {
 const payload = {
 sub: 'mch_test',
Expand Down
Loading

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
}
/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
[data-theme="light"], [data-theme="light"],
.ace_editor, .ace_editor *,
.CodeMirror, .CodeMirror *,
.monaco-editor, .monaco-editor *,
.markdown-body pre, .markdown-body pre *,
.highlight, .highlight *,
pre code, pre code * {
filter: none !important;
}
/* Fix common UI elements */
.modal, .popup, .dropdown-menu, .tooltip, .popover {
filter: invert(1) hue-rotate(180deg) !important;
background: #2d2d44 !important;
border-color: #444 !important;
}
/* Scrollbars */
::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
if (style) style.remove();
}
// Toggle with Alt+Shift+D
document.addEventListener('keydown', function(e) {
if (e.altKey && e.shiftKey && e.key === 'D') {
e.preventDefault();
enabled = !enabled;
if (enabled) {
applyDarkMode();
console.log('[Universal Dark Mode] Enabled');
} else {
removeDarkMode();
console.log('[Universal Dark Mode] Disabled');
}
}
});
// Apply on load
applyDarkMode();
// Re-apply on dynamic content
var observer = new MutationObserver(function(mutations) {
if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
}
});
observer.observe(document.head, { childList: true });
console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();
fix(backend): preserve custom claims when verifying JWT M2M tokens by jacekradko · Pull Request #8697 · clerk/javascript · GitHub
Skip to content
fix(backend): preserve custom claims when verifying JWT M2M tokens#8697

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 Merged

jacekradko
merged 2 commits into

from

May 29, 2026
 Merged


fix(backend): preserve custom claims when verifying JWT M2M tokens
#8697
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2970146

fix(backend): preserve custom claims when verifying JWT M2M tokens


jacekradko May 28, 2026
95eb4a9

update claims handling


jacekradko May 29, 2026

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5 changes: 5 additions & 0 deletions
.changeset/m2m-jwt-custom-claims.md

View file


Open in desktop

Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
---
'@clerk/backend': patch
---

Preserve custom claims when verifying JWT-format M2M tokens. `M2MToken.fromJwtPayload` previously hardcoded `claims` to `null`, so `client.m2m.verify()` (and request-level `auth()`) dropped any custom claims embedded in the token. Custom claims are now reconstructed from the verified payload by stripping only the structural claims the backend adds when minting the token (`iss`, `sub`, `exp`, `nbf`, `iat`, `jti`). User-supplied claims such as `aud` are preserved. Tokens without custom claims still return `claims: null`, consistent with the opaque-token path.

33 changes: 32 additions & 1 deletion
packages/backend/src/api/__tests__/M2MTokenApi.test.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -417,7 +417,7 @@ describe('M2MToken', () => {
 });
 });

 async function createSignedM2MJwt(payload = mockM2MJwtPayload) {
 async function createSignedM2MJwt(payload: Record<string, unknown> = mockM2MJwtPayload) {
 const { data } = await signJwt(payload, signingJwks, {
 algorithm: 'RS256',
 header: { typ: 'JWT', kid: 'ins_2GIoQhbUpy0hX7B2cVkuTMinXoD' },
Expand DownExpand Up@@ -455,6 +455,37 @@ describe('M2MToken', () => {
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('preserves custom claims embedded in a JWT M2M token', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
 { secretKey: 'sk_test_xxxxx', apiUrl: 'https://api.clerk.test', skipJwksCache: true },
 );

 server.use(
 http.get(
 'https://api.clerk.test/v1/jwks',
 validateHeaders(() => HttpResponse.json(mockJwks)),
 ),
 );

 const jwtToken = await createSignedM2MJwt({
 ...mockM2MJwtPayload,
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 const result = await m2mApi.verify({ token: jwtToken });

 // `aud` and `scopes` from the token are user-supplied custom claims and are
 // preserved in `claims`; `scopes` additionally seeds the dedicated field.
 expect(result.claims).toEqual({
 aud: ['mch_1xxxxx', 'mch_2xxxxx'],
 scopes: 'mch_1xxxxx mch_2xxxxx',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 expect(result.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 });

 it('throws when JWT signature cannot be verified', async () => {
 const m2mApi = new M2MTokenApi(
 buildRequest({ apiUrl: 'https://api.clerk.test', skipApiVersionInUrl: true, requireSecretKey: false }),
Expand Down

26 changes: 25 additions & 1 deletion
packages/backend/src/api/resources/M2MToken.ts

View file


Open in desktop

Original file line numberDiff line numberDiff line change
Expand Up@@ -12,6 +12,30 @@ type M2MJwtPayload = {
 [key: string]: unknown;
};

// Structural claims that Clerk's machine-token service always adds when it mints
// an M2M JWT. These are mapped onto dedicated `M2MToken` fields, so they are
// stripped from `claims`. Everything else is a user-supplied custom claim and is
// surfaced through `claims`, including `aud` and `scopes`, which the backend
// treats as custom claims (they are neither reserved nor auto-added).
const M2M_RESERVED_JWT_CLAIMS = new Set(['iss', 'sub', 'exp', 'nbf', 'iat', 'jti']);

/**
 * Reconstructs the custom claims that were attached at token creation by
 * stripping the structural claims (see `M2M_RESERVED_JWT_CLAIMS`) from the
 * verified payload. Returns `null` when no custom claims are present, matching
 * the opaque-token path where a token created without claims verifies back to
 * `claims: null`.
 */
function extractCustomClaims(payload: M2MJwtPayload): Record<string, any> | null {
 const claims: Record<string, any> = {};
 for (const key of Object.keys(payload)) {
 if (!M2M_RESERVED_JWT_CLAIMS.has(key)) {
 claims[key] = payload[key];
 }
 }
 return Object.keys(claims).length > 0 ? claims : null;
}

/**
 * The Backend `M2MToken` object holds information about a machine-to-machine token.
 */
Expand DownExpand Up@@ -51,7 +75,7 @@ export class M2MToken {
 payload.jti ?? '', // jti should always be present in Clerk-issued M2M JWTs
 payload.sub,
 payload.scopes?.split(' ') ?? payload.aud ?? [],
null,
extractCustomClaims(payload),
 false,
 null,
 payload.exp * 1000 <= Date.now() - clockSkewInMs,
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40 changes: 39 additions & 1 deletion
packages/backend/src/api/resources/__tests__/M2MToken.test.ts

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Original file line numberDiff line numberDiff line change
Expand Up@@ -29,7 +29,9 @@ describe('M2MToken', () => {
 expect(token.id).toBe('mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE');
 expect(token.subject).toBe('mch_2vYVtestTESTtestTESTtestTESTtest');
 expect(token.scopes).toEqual(['mch_1xxxxx', 'mch_2xxxxx']);
 expect(token.claims).toBeNull();
 // `aud` is a user-supplied custom claim (the backend does not auto-add it),
 // so it is surfaced through `claims` while also seeding the `scopes` field.
 expect(token.claims).toEqual({ aud: ['mch_1xxxxx', 'mch_2xxxxx'] });
 expect(token.revoked).toBe(false);
 expect(token.revocationReason).toBeNull();
 expect(token.expired).toBe(false);
Expand All@@ -38,6 +40,42 @@ describe('M2MToken', () => {
 expect(token.updatedAt).toBe(1666648250 * 1000);
 });

 it('preserves custom claims (including aud and scopes) and strips only structural claims', () => {
 const payload = {
 iss: 'https://clerk.m2m.example.test',
 sub: 'mch_2vYVtestTESTtestTESTtestTESTtest',
 aud: ['mch_1xxxxx'],
 exp: 1666648550,
 iat: 1666648250,
 nbf: 1666648240,
 jti: 'mt_2xKa9Bgv7NxMRDFyQw8LpZ3cTmU1vHjE',
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 };

 const token = M2MToken.fromJwtPayload(payload);

 // `aud` and `scopes` are user-supplied custom claims in Clerk-issued M2M
 // tokens (the backend neither reserves nor auto-adds them), so they are
 // preserved in `claims` alongside any other custom claims.
 expect(token.claims).toEqual({
 aud: ['mch_1xxxxx'],
 scopes: 'scope1 scope2',
 permissions: ['read:users', 'read:orders'],
 role: 'service',
 });
 // Structural claims are mapped to dedicated fields, not leaked into `claims`.
 expect(token.claims).not.toHaveProperty('iss');
 expect(token.claims).not.toHaveProperty('sub');
 expect(token.claims).not.toHaveProperty('exp');
 expect(token.claims).not.toHaveProperty('nbf');
 expect(token.claims).not.toHaveProperty('iat');
 expect(token.claims).not.toHaveProperty('jti');
 // `scopes` is still derived onto the dedicated `scopes` field.
 expect(token.scopes).toEqual(['scope1', 'scope2']);
 });

 it('prefers scopes claim over aud when both are present', () => {
 const payload = {
 sub: 'mch_test',
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