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fix(security): record dependencies without walking into the prototype - #13
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`depmap[parent] = depmap[parent] || {}` indexes by SOURCE PATH, so the
key is only as trustworthy as the tree being resolved. On an ordinary
object `depmap['__proto__']` answers with `Object.prototype` — truthy,
so the `||` never fires and the dependency is recorded onto the
prototype of every object in the process.
The map is caller-supplied via `msmeta.deps`, so its prototype is not
ours to remove. Instead the read is an own-property check, which stops
an inherited name masquerading as an existing entry, and the write is a
`defineProperty`, which creates an own property rather than invoking the
`__proto__` setter.
Suite unchanged: 35 tests, 0 failures.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KeS3Phjrv21moqauXAdhfrUh oh!
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Found by an org-wide sweep for the idiom that was live in
@jsonic/toml.depmap[parent] = depmap[parent] || {}indexes by source path, so the key is only as trustworthy as the tree being resolved. On an ordinary objectdepmap['__proto__']answers withObject.prototype— truthy, so the||never fires and the dependency is recorded onto the prototype of every object in the process.Lower severity than the toml case: it needs a source path that is exactly
__proto__, not merely a document you did not write.The map is caller-supplied via
msmeta.deps, so its prototype is not ours to remove. Instead the read is an own-property check, which stops an inherited name masquerading as an existing entry, and the write is adefineProperty, which creates an own property rather than invoking the__proto__setter.Suite unchanged: 35 tests, 0 failures.
🤖 Generated with Claude Code
https://claude.ai/code/session_01KeS3Phjrv21moqauXAdhfr