{"id":"GHSA-28xv-ph75-77wh","summary":"Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__","details":"### Impact\n\nThe `_.merge(target, source)` utility exported by `@feathersjs/commons` recursively merges `source` into `target` by iterating `Object.keys(source)`. When `source` was produced by `JSON.parse` and contains a `__proto__` (or `constructor` / `prototype`) key, that key is returned as an own-enumerable property. The recursive merge then resolves `target['__proto__']` to `Object.prototype` and writes the attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process.\n\n**Scope of real-world risk is limited.** No first-party Feathers package routes input — trusted or untrusted — through `commons._.merge`. The `@feathersjs/authentication` package, which does merge request-influenced data, uses `lodash/merge` (prototype-pollution-safe since 4.17.12), not this utility. Exploitation therefore requires a downstream plugin or application to pass JSON-parsed, attacker-controlled input directly through the exported `_.merge`.\n\n### Patches\n\nFixed in `@feathersjs/commons@5.0.45`. The fix skips `__proto__`, `constructor`, and `prototype` keys during iteration — the standard remediation used by lodash and others.\n\n### Workarounds\n\nAvoid passing JSON-parsed untrusted input through `commons._.merge`. Freezing `Object.prototype` or validating/sanitizing keys upstream also mitigates.\n\n### Credit\n\nReported responsibly by Andrew Ridings (@ridingsa).","aliases":["CVE-2026-54335"],"modified":"2026-07-14T19:56:45.565577Z","published":"2026-07-14T19:40:05Z","database_specific":{"github_reviewed_at":"2026-07-14T19:40:05Z","nvd_published_at":null,"cwe_ids":["CWE-1321"],"severity":"LOW","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/feathersjs/feathers/security/advisories/GHSA-28xv-ph75-77wh"},{"type":"WEB","url":"https://github.com/feathersjs/feathers/pull/3690"},{"type":"WEB","url":"https://github.com/feathersjs/feathers/commit/28b3c03c63bdbff53115fdaa46c56980e7942acc"},{"type":"PACKAGE","url":"https://github.com/feathersjs/feathers"},{"type":"WEB","url":"https://github.com/feathersjs/feathers/releases/tag/v5.0.45"}],"affected":[{"package":{"name":"@feathersjs/commons","ecosystem":"npm","purl":"pkg:npm/%40feathersjs/commons"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"5.0.45"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 5.0.44","source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-28xv-ph75-77wh/GHSA-28xv-ph75-77wh.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"}]}