Skip to content

fix: prevent streamable HTTP session leak - #934

Merged
DaleSeo merged 1 commit into
mainfrom
fix/streamable-http-session-leak
Jun 27, 2026
Merged

fix: prevent streamable HTTP session leak#934
DaleSeo merged 1 commit into
mainfrom
fix/streamable-http-session-leak

Conversation

@DaleSeo

@DaleSeoDaleSeo commented Jun 26, 2026

Copy link
Copy Markdown
Member

Motivation and Context

The stateful Streamable HTTP server could allocate a local session before rejecting an invalid initial POST. This change validates that an initial stateful POST is an initialize request, checks the MCP-Protocol-Version header against the initialize body, and only creates a session after those checks pass. That keeps rejected pre-initialize requests from leaving entries behind in LocalSessionManager.

How Has This Been Tested?

Added tests

Breaking Changes

None.

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Documentation update

Checklist

  • I have read the MCP Documentation
  • My code follows the repository's style guidelines
  • New and existing tests pass locally
  • I have added appropriate error handling
  • I have added or updated documentation as needed

@github-actionsgithub-actionsBot added T-test Testing related changes T-core Core library changes T-transport Transport layer changes labels Jun 26, 2026
@DaleSeo
DaleSeo marked this pull request as ready for review June 26, 2026 21:37
@DaleSeo
DaleSeo requested a review from a team as a code ownerJune 26, 2026 21:37
@DaleSeoDaleSeo self-assigned this Jun 27, 2026
@DaleSeo
DaleSeo merged commit dfa7fd6 into mainJun 27, 2026
19 checks passed
@DaleSeo
DaleSeo deleted the fix/streamable-http-session-leak branch June 27, 2026 01:09
@github-actionsgithub-actionsBot mentioned this pull request Jun 26, 2026
Merged
@cyberlife-codercyberlife-coder mentioned this pull request Jun 30, 2026
Closed
8 tasks
@alphabet-halphabet-h mentioned this pull request Aug 14, 2026
Merged
alphabet-h added a commit to alphabet-h/grooveseek that referenced this pull request Aug 14, 2026
@alphabet-h
docs(changelog): note that rmcp fixed the session leak in 2.0.0 (BU-3…
646f1ac
…2) (#149)
Reported against 1.4.0 as modelcontextprotocol/rust-sdk#808 and fixed by modelcontextprotocol/rust-sdk#934, released in rmcp 2.0.0, which also added SessionConfig::init_timeout. Verified against the published crates: 1.4.0-1.8.0 create the session before the initialize check, 2.0.0 onward do not. kb-mcp still pins 1.4.0, and no rmcp release bounds the number of sessions.
@alphabet-halphabet-h mentioned this pull request Aug 14, 2026
Merged
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@jokemanfirejokemanfirejokemanfire approved these changes

Assignees

@DaleSeoDaleSeo

Labels

T-coreCore library changesT-testTesting related changesT-transportTransport layer changes

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

2 participants

@DaleSeo@jokemanfire
, '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);
});
};
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: prevent streamable HTTP session leak by DaleSeo · Pull Request #934 · modelcontextprotocol/rust-sdk · GitHub
Skip to content
fix: prevent streamable HTTP session leak - #934
Merged
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Jun 27, 2026
Merged
fix: prevent streamable HTTP session leak#934
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Conversation
@DaleSeo
@DaleSeoDaleSeo
commented
Jun 26, 2026

Copy link


Copy Markdown

Member
Motivation and Context
The stateful Streamable HTTP server could allocate a local session before rejecting an invalid initial POST. This change validates that an initial stateful POST is an initialize request, checks the MCP-Protocol-Version header against the initialize body, and only creates a session after those checks pass. That keeps rejected pre-initialize requests from leaving entries behind in LocalSessionManager.
How Has This Been Tested?
Added tests
Breaking Changes
None.
Types of changes
  •  Bug fix (non-breaking change which fixes an issue)
  •  New feature (non-breaking change which adds functionality)
  •  Breaking change (fix or feature that would cause existing functionality to change)
  •  Documentation update
Checklist
  •  I have read the MCP Documentation
  •  My code follows the repository's style guidelines
  •  New and existing tests pass locally
  •  I have added appropriate error handling
  •  I have added or updated documentation as needed
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-core
Core library changes
T-transport
Transport layer changes
labels
Jun 26, 2026
@DaleSeo
DaleSeo
marked this pull request as ready for review
June 26, 2026 21:37
@DaleSeo
DaleSeo
requested a review
from a team
as a code ownerJune 26, 2026 21:37
@DaleSeoDaleSeo
self-assigned this
Jun 27, 2026
@DaleSeo
DaleSeo
merged commit dfa7fd6
into
mainJun 27, 2026

19 checks passed

@DaleSeo
DaleSeo
deleted the

fix/streamable-http-session-leak

branch
June 27, 2026 01:09
@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
 Merged

@cyberlife-codercyberlife-coder
mentioned this pull request
Jun 30, 2026
 Closed

8 tasks
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

alphabet-h added a commit
to alphabet-h/grooveseek
that referenced
this pull request
Aug 14, 2026
@alphabet-h
docs(changelog): note that rmcp fixed the session leak in 2.0.0 (BU-3…
646f1ac
…2) (#149)
Reported against 1.4.0 as modelcontextprotocol/rust-sdk#808 and fixed by modelcontextprotocol/rust-sdk#934, released in rmcp 2.0.0, which also added SessionConfig::init_timeout. Verified against the published crates: 1.4.0-1.8.0 create the session before the initialize check, 2.0.0 onward do not. kb-mcp still pins 1.4.0, and no rmcp release bounds the number of sessions.
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@jokemanfirejokemanfirejokemanfire approved these changes

Assignees

@DaleSeoDaleSeo

Labels

T-coreCore library changesT-testTesting related changesT-transportTransport layer changes

Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

2 participants

@DaleSeo@jokemanfire

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Force GitHub README to respect dark mode
(function() {
var style = document.createElement('style');
style.textContent = '
.markdown-body {
color-scheme: dark light;
}
.markdown-body pre { background: #161b22 !important; }
.markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }
.markdown-body table th, .markdown-body table td { border-color: #30363d !important; }
.markdown-body img { background: #0d1117; }
.markdown-body blockquote { border-left-color: #8b949e; }
.markdown-body hr { border-color: #30363d; }
';
document.head.appendChild(style);
})();
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
fix: prevent streamable HTTP session leak by DaleSeo · Pull Request #934 · modelcontextprotocol/rust-sdk · GitHub
Skip to content
fix: prevent streamable HTTP session leak - #934
Merged
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Jun 27, 2026
Merged
fix: prevent streamable HTTP session leak#934
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Conversation
@DaleSeo
@DaleSeoDaleSeo
commented
Jun 26, 2026

Copy link


Copy Markdown

Member
Motivation and Context
The stateful Streamable HTTP server could allocate a local session before rejecting an invalid initial POST. This change validates that an initial stateful POST is an initialize request, checks the MCP-Protocol-Version header against the initialize body, and only creates a session after those checks pass. That keeps rejected pre-initialize requests from leaving entries behind in LocalSessionManager.
How Has This Been Tested?
Added tests
Breaking Changes
None.
Types of changes
  •  Bug fix (non-breaking change which fixes an issue)
  •  New feature (non-breaking change which adds functionality)
  •  Breaking change (fix or feature that would cause existing functionality to change)
  •  Documentation update
Checklist
  •  I have read the MCP Documentation
  •  My code follows the repository's style guidelines
  •  New and existing tests pass locally
  •  I have added appropriate error handling
  •  I have added or updated documentation as needed
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-core
Core library changes
T-transport
Transport layer changes
labels
Jun 26, 2026
@DaleSeo
DaleSeo
marked this pull request as ready for review
June 26, 2026 21:37
@DaleSeo
DaleSeo
requested a review
from a team
as a code ownerJune 26, 2026 21:37
@DaleSeoDaleSeo
self-assigned this
Jun 27, 2026
@DaleSeo
DaleSeo
merged commit dfa7fd6
into
mainJun 27, 2026

19 checks passed

@DaleSeo
DaleSeo
deleted the

fix/streamable-http-session-leak

branch
June 27, 2026 01:09
@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
 Merged

@cyberlife-codercyberlife-coder
mentioned this pull request
Jun 30, 2026
 Closed

8 tasks
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

alphabet-h added a commit
to alphabet-h/grooveseek
that referenced
this pull request
Aug 14, 2026
@alphabet-h
docs(changelog): note that rmcp fixed the session leak in 2.0.0 (BU-3…
646f1ac
…2) (#149)
Reported against 1.4.0 as modelcontextprotocol/rust-sdk#808 and fixed by modelcontextprotocol/rust-sdk#934, released in rmcp 2.0.0, which also added SessionConfig::init_timeout. Verified against the published crates: 1.4.0-1.8.0 create the session before the initialize check, 2.0.0 onward do not. kb-mcp still pins 1.4.0, and no rmcp release bounds the number of sessions.
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@jokemanfirejokemanfirejokemanfire approved these changes

Assignees

@DaleSeoDaleSeo

Labels

T-coreCore library changesT-testTesting related changesT-transportTransport layer changes

Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

2 participants

@DaleSeo@jokemanfire

, '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: prevent streamable HTTP session leak by DaleSeo · Pull Request #934 · modelcontextprotocol/rust-sdk · GitHub
Skip to content
fix: prevent streamable HTTP session leak - #934
Merged
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Jun 27, 2026
Merged
fix: prevent streamable HTTP session leak#934
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Conversation
@DaleSeo
@DaleSeoDaleSeo
commented
Jun 26, 2026

Copy link


Copy Markdown

Member
Motivation and Context
The stateful Streamable HTTP server could allocate a local session before rejecting an invalid initial POST. This change validates that an initial stateful POST is an initialize request, checks the MCP-Protocol-Version header against the initialize body, and only creates a session after those checks pass. That keeps rejected pre-initialize requests from leaving entries behind in LocalSessionManager.
How Has This Been Tested?
Added tests
Breaking Changes
None.
Types of changes
  •  Bug fix (non-breaking change which fixes an issue)
  •  New feature (non-breaking change which adds functionality)
  •  Breaking change (fix or feature that would cause existing functionality to change)
  •  Documentation update
Checklist
  •  I have read the MCP Documentation
  •  My code follows the repository's style guidelines
  •  New and existing tests pass locally
  •  I have added appropriate error handling
  •  I have added or updated documentation as needed
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-core
Core library changes
T-transport
Transport layer changes
labels
Jun 26, 2026
@DaleSeo
DaleSeo
marked this pull request as ready for review
June 26, 2026 21:37
@DaleSeo
DaleSeo
requested a review
from a team
as a code ownerJune 26, 2026 21:37
@DaleSeoDaleSeo
self-assigned this
Jun 27, 2026
@DaleSeo
DaleSeo
merged commit dfa7fd6
into
mainJun 27, 2026

19 checks passed

@DaleSeo
DaleSeo
deleted the

fix/streamable-http-session-leak

branch
June 27, 2026 01:09
@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
 Merged

@cyberlife-codercyberlife-coder
mentioned this pull request
Jun 30, 2026
 Closed

8 tasks
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

alphabet-h added a commit
to alphabet-h/grooveseek
that referenced
this pull request
Aug 14, 2026
@alphabet-h
docs(changelog): note that rmcp fixed the session leak in 2.0.0 (BU-3…
646f1ac
…2) (#149)
Reported against 1.4.0 as modelcontextprotocol/rust-sdk#808 and fixed by modelcontextprotocol/rust-sdk#934, released in rmcp 2.0.0, which also added SessionConfig::init_timeout. Verified against the published crates: 1.4.0-1.8.0 create the session before the initialize check, 2.0.0 onward do not. kb-mcp still pins 1.4.0, and no rmcp release bounds the number of sessions.
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@jokemanfirejokemanfirejokemanfire approved these changes

Assignees

@DaleSeoDaleSeo

Labels

T-coreCore library changesT-testTesting related changesT-transportTransport layer changes

Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

2 participants

@DaleSeo@jokemanfire

, '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: prevent streamable HTTP session leak by DaleSeo · Pull Request #934 · modelcontextprotocol/rust-sdk · GitHub
Skip to content
fix: prevent streamable HTTP session leak - #934
Merged
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Jun 27, 2026
Merged
fix: prevent streamable HTTP session leak#934
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Conversation
@DaleSeo
@DaleSeoDaleSeo
commented
Jun 26, 2026

Copy link


Copy Markdown

Member
Motivation and Context
The stateful Streamable HTTP server could allocate a local session before rejecting an invalid initial POST. This change validates that an initial stateful POST is an initialize request, checks the MCP-Protocol-Version header against the initialize body, and only creates a session after those checks pass. That keeps rejected pre-initialize requests from leaving entries behind in LocalSessionManager.
How Has This Been Tested?
Added tests
Breaking Changes
None.
Types of changes
  •  Bug fix (non-breaking change which fixes an issue)
  •  New feature (non-breaking change which adds functionality)
  •  Breaking change (fix or feature that would cause existing functionality to change)
  •  Documentation update
Checklist
  •  I have read the MCP Documentation
  •  My code follows the repository's style guidelines
  •  New and existing tests pass locally
  •  I have added appropriate error handling
  •  I have added or updated documentation as needed
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-core
Core library changes
T-transport
Transport layer changes
labels
Jun 26, 2026
@DaleSeo
DaleSeo
marked this pull request as ready for review
June 26, 2026 21:37
@DaleSeo
DaleSeo
requested a review
from a team
as a code ownerJune 26, 2026 21:37
@DaleSeoDaleSeo
self-assigned this
Jun 27, 2026
@DaleSeo
DaleSeo
merged commit dfa7fd6
into
mainJun 27, 2026

19 checks passed

@DaleSeo
DaleSeo
deleted the

fix/streamable-http-session-leak

branch
June 27, 2026 01:09
@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
 Merged

@cyberlife-codercyberlife-coder
mentioned this pull request
Jun 30, 2026
 Closed

8 tasks
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

alphabet-h added a commit
to alphabet-h/grooveseek
that referenced
this pull request
Aug 14, 2026
@alphabet-h
docs(changelog): note that rmcp fixed the session leak in 2.0.0 (BU-3…
646f1ac
…2) (#149)
Reported against 1.4.0 as modelcontextprotocol/rust-sdk#808 and fixed by modelcontextprotocol/rust-sdk#934, released in rmcp 2.0.0, which also added SessionConfig::init_timeout. Verified against the published crates: 1.4.0-1.8.0 create the session before the initialize check, 2.0.0 onward do not. kb-mcp still pins 1.4.0, and no rmcp release bounds the number of sessions.
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@jokemanfirejokemanfirejokemanfire approved these changes

Assignees

@DaleSeoDaleSeo

Labels

T-coreCore library changesT-testTesting related changesT-transportTransport layer changes

Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

2 participants

@DaleSeo@jokemanfire

, '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: prevent streamable HTTP session leak by DaleSeo · Pull Request #934 · modelcontextprotocol/rust-sdk · GitHub
Skip to content
fix: prevent streamable HTTP session leak - #934
Merged
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Jun 27, 2026
Merged
fix: prevent streamable HTTP session leak#934
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Conversation
@DaleSeo
@DaleSeoDaleSeo
commented
Jun 26, 2026

Copy link


Copy Markdown

Member
Motivation and Context
The stateful Streamable HTTP server could allocate a local session before rejecting an invalid initial POST. This change validates that an initial stateful POST is an initialize request, checks the MCP-Protocol-Version header against the initialize body, and only creates a session after those checks pass. That keeps rejected pre-initialize requests from leaving entries behind in LocalSessionManager.
How Has This Been Tested?
Added tests
Breaking Changes
None.
Types of changes
  •  Bug fix (non-breaking change which fixes an issue)
  •  New feature (non-breaking change which adds functionality)
  •  Breaking change (fix or feature that would cause existing functionality to change)
  •  Documentation update
Checklist
  •  I have read the MCP Documentation
  •  My code follows the repository's style guidelines
  •  New and existing tests pass locally
  •  I have added appropriate error handling
  •  I have added or updated documentation as needed
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-core
Core library changes
T-transport
Transport layer changes
labels
Jun 26, 2026
@DaleSeo
DaleSeo
marked this pull request as ready for review
June 26, 2026 21:37
@DaleSeo
DaleSeo
requested a review
from a team
as a code ownerJune 26, 2026 21:37
@DaleSeoDaleSeo
self-assigned this
Jun 27, 2026
@DaleSeo
DaleSeo
merged commit dfa7fd6
into
mainJun 27, 2026

19 checks passed

@DaleSeo
DaleSeo
deleted the

fix/streamable-http-session-leak

branch
June 27, 2026 01:09
@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
 Merged

@cyberlife-codercyberlife-coder
mentioned this pull request
Jun 30, 2026
 Closed

8 tasks
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

alphabet-h added a commit
to alphabet-h/grooveseek
that referenced
this pull request
Aug 14, 2026
@alphabet-h
docs(changelog): note that rmcp fixed the session leak in 2.0.0 (BU-3…
646f1ac
…2) (#149)
Reported against 1.4.0 as modelcontextprotocol/rust-sdk#808 and fixed by modelcontextprotocol/rust-sdk#934, released in rmcp 2.0.0, which also added SessionConfig::init_timeout. Verified against the published crates: 1.4.0-1.8.0 create the session before the initialize check, 2.0.0 onward do not. kb-mcp still pins 1.4.0, and no rmcp release bounds the number of sessions.
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@jokemanfirejokemanfirejokemanfire approved these changes

Assignees

@DaleSeoDaleSeo

Labels

T-coreCore library changesT-testTesting related changesT-transportTransport layer changes

Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

2 participants

@DaleSeo@jokemanfire

, '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); }
})();
})();
fix: prevent streamable HTTP session leak by DaleSeo · Pull Request #934 · modelcontextprotocol/rust-sdk · GitHub
Skip to content
fix: prevent streamable HTTP session leak - #934
Merged
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Jun 27, 2026
Merged
fix: prevent streamable HTTP session leak#934
DaleSeo merged 1 commit into
mainfrom 
fix/streamable-http-session-leak
Conversation
@DaleSeo
@DaleSeoDaleSeo
commented
Jun 26, 2026

Copy link


Copy Markdown

Member
Motivation and Context
The stateful Streamable HTTP server could allocate a local session before rejecting an invalid initial POST. This change validates that an initial stateful POST is an initialize request, checks the MCP-Protocol-Version header against the initialize body, and only creates a session after those checks pass. That keeps rejected pre-initialize requests from leaving entries behind in LocalSessionManager.
How Has This Been Tested?
Added tests
Breaking Changes
None.
Types of changes
  •  Bug fix (non-breaking change which fixes an issue)
  •  New feature (non-breaking change which adds functionality)
  •  Breaking change (fix or feature that would cause existing functionality to change)
  •  Documentation update
Checklist
  •  I have read the MCP Documentation
  •  My code follows the repository's style guidelines
  •  New and existing tests pass locally
  •  I have added appropriate error handling
  •  I have added or updated documentation as needed
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-core
Core library changes
T-transport
Transport layer changes
labels
Jun 26, 2026
@DaleSeo
DaleSeo
marked this pull request as ready for review
June 26, 2026 21:37
@DaleSeo
DaleSeo
requested a review
from a team
as a code ownerJune 26, 2026 21:37
@DaleSeoDaleSeo
self-assigned this
Jun 27, 2026
@DaleSeo
DaleSeo
merged commit dfa7fd6
into
mainJun 27, 2026

19 checks passed

@DaleSeo
DaleSeo
deleted the

fix/streamable-http-session-leak

branch
June 27, 2026 01:09
@github-actionsgithub-actionsBot
mentioned this pull request
Jun 26, 2026
 Merged

@cyberlife-codercyberlife-coder
mentioned this pull request
Jun 30, 2026
 Closed

8 tasks
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

alphabet-h added a commit
to alphabet-h/grooveseek
that referenced
this pull request
Aug 14, 2026
@alphabet-h
docs(changelog): note that rmcp fixed the session leak in 2.0.0 (BU-3…
646f1ac
…2) (#149)
Reported against 1.4.0 as modelcontextprotocol/rust-sdk#808 and fixed by modelcontextprotocol/rust-sdk#934, released in rmcp 2.0.0, which also added SessionConfig::init_timeout. Verified against the published crates: 1.4.0-1.8.0 create the session before the initialize check, 2.0.0 onward do not. kb-mcp still pins 1.4.0, and no rmcp release bounds the number of sessions.
@alphabet-halphabet-h
mentioned this pull request
Aug 14, 2026
 Merged

Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@jokemanfirejokemanfirejokemanfire approved these changes

Assignees

@DaleSeoDaleSeo

Labels

T-coreCore library changesT-testTesting related changesT-transportTransport layer changes

Projects


None yet


Milestone


No milestone


Development

Successfully merging this pull request may close these issues.

2 participants

@DaleSeo@jokemanfire