{"id":"CVE-2026-54335","aliases":["GHSA-28xv-ph75-77wh"],"url":"https://o3.security/vulnerability/CVE-2026-54335","summary":"Feathersjs: 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).","published":"2026-07-17T20:56:51.857Z","modified":"2026-08-12T03:51:14.201881861Z","cvss":{"score":3.7,"severity":"LOW","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N"},"epss":{"score":0.00389,"percentile":0.32716,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@feathersjs/commons","fixedVersion":"5.0.45"}],"fix":{"url":"https://github.com/feathersjs/feathers/commit/28b3c03c63bdbff53115fdaa46c56980e7942acc","label":"feathersjs/feathers@28b3c03"},"references":[{"type":"WEB","url":"https://github.com/feathersjs/feathers/releases/tag/v5.0.45"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54335.json"},{"type":"ADVISORY","url":"https://github.com/feathersjs/feathers/security/advisories/GHSA-28xv-ph75-77wh"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54335"},{"type":"FIX","url":"https://github.com/feathersjs/feathers/commit/28b3c03c63bdbff53115fdaa46c56980e7942acc"},{"type":"FIX","url":"https://github.com/feathersjs/feathers/pull/3690"},{"type":"PACKAGE","url":"https://github.com/feathersjs/feathers"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:14.201881861Z"}}