fix: refuse prototype-polluting mount-path segments in api.add() - #305
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A dotted or array mount path passed to api.slothlet.api.add() was split into segments and written into the api tree without guarding prototype-chain segment names. A path containing __proto__, constructor, or prototype therefore mutated Object.prototype / Function.prototype globally instead of the api tree — classic prototype pollution — with no error raised. normalizeApiPath now refuses any of these three names in any segment position (both the dotted-string and array path forms) with INVALID_CONFIG_API_PATH_INVALID and the new API_PATH_REASON_UNSAFE_SEGMENT reason, mirroring the existing reserved-name guard. Adds the reason string to all 12 language packs and coverage for both path forms plus a no-pollution assertion. This corrects never-intended behavior (a silent global write), so it ships as a patch — no legitimate consumer mounts at __proto__/constructor/prototype. Fixes #302
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Pull request overview
This PR hardens ApiManager.normalizeApiPath() to reject prototype-polluting mount-path segments (__proto__, constructor, prototype) so api.add() can’t mutate the JS prototype chain when constructing the mounted API tree.
Changes:
- Add a normalization-time guard that refuses unsafe path segments in any position for both string and array apiPath forms.
- Add Vitest coverage for rejecting unsafe segments and verifying no
Object.prototypepollution. - Add a new i18n reason string (
API_PATH_REASON_UNSAFE_SEGMENT) across all locales.
Reviewed changes
Copilot reviewed 14 out of 14 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| tests/vitests/suites/api-manager/api-manager-reserved-paths.test.vitest.mjs | Adds test cases for unsafe segments and prototype-pollution prevention. |
| src/lib/handlers/api-manager.mjs | Introduces UNSAFE_PATH_SEGMENTS and rejects unsafe segments during path normalization. |
| src/lib/i18n/languages/en-us.json | Adds new error reason string for unsafe segments. |
| src/lib/i18n/languages/en-gb.json | Adds new error reason string for unsafe segments. |
| src/lib/i18n/languages/de-de.json | Adds translation for the new unsafe-segment reason. |
| src/lib/i18n/languages/es-es.json | Adds translation for the new unsafe-segment reason. |
| src/lib/i18n/languages/es-mx.json | Adds translation for the new unsafe-segment reason. |
| src/lib/i18n/languages/fr-fr.json | Adds translation for the new unsafe-segment reason. |
| src/lib/i18n/languages/hi-in.json | Adds translation for the new unsafe-segment reason. |
| src/lib/i18n/languages/ja-jp.json | Adds translation for the new unsafe-segment reason. |
| src/lib/i18n/languages/ko-kr.json | Adds translation for the new unsafe-segment reason. |
| src/lib/i18n/languages/pt-br.json | Adds translation for the new unsafe-segment reason. |
| src/lib/i18n/languages/ru-ru.json | Adds translation for the new unsafe-segment reason. |
| src/lib/i18n/languages/zh-cn.json | Adds translation for the new unsafe-segment reason. |
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The prototype-pollution guard added to normalizeApiPath preempted the dedicated
LOOSE_SET_RESERVED_KEY error that setOwnedProperty raises for `self.<key> = …`
assignments: setOwnedProperty calls normalizeApiPath first, so a
`self.prototype = {}` / `self['__proto__'] = obj` now threw the generic
INVALID_CONFIG_API_PATH_INVALID instead, breaking
runtime/self-assign-prototype-pollution.
Run the reserved-segment check (LOOSE_SET_RESERVED_KEY) before normalizeApiPath
so the self-assign surface keeps its own error while the api.add() mount-path
surface keeps the new unsafe-segment error. Both guards stay reachable and tested.
Address Copilot review on #305: - The "__-prefixed still accepted" test mounted at "plugins", so it never exercised a __-prefixed segment. Mount "__config.value" and a ["prototypeName","leaf"] substring path instead, proving the guard matches whole segments (only __proto__/constructor/prototype), not prefixes/substrings. - Capitalize the ru-ru API_PATH_REASON_UNSAFE_SEGMENT string to match that locale's sentence-cased sibling messages.
Shinrai
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that referenced
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Aug 24, 2026
… keepers The three slothlet bugs found while building vine now have fix PRs (CLDMV/slothlet#305/#306/#307 for issues #302/#303/#304). Update the code comments to reference them — but the guards STAY, and the comments now say why: - frame.mjs UNSAFE_SEGMENTS is security (validating untrusted REMOTE surface paths at vine's boundary), not a bug workaround — independent of the slothlet version. - grow.mjs hyphen moduleID is zero-cost and works on patched + unpatched slothlet. - serve.mjs Reflect.apply is idiomatic and shadow-proof — better than leaf.apply even once #307 lands. No behavior change; 330 tests green.
…dProperty Address Copilot review on #305: the loose-set prototype-pollution guard allocated a fresh Set on every call and coerced via a template literal, which throws a raw TypeError on a Symbol instead of the intended SlothletError path. Reuse the module-level UNSAFE_PATH_SEGMENTS and coerce with String() — branchless and Symbol-safe.
Shinrai
approved these changes
Aug 24, 2026
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