{"id":"CVE-2026-54335","aliases":["EUVD-2026-45337","GHSA-28xv-ph75-77wh"],"status":"published","title":"Feathersjs: Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__","description":"Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. In 5.0.44 and earlier, the _.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__, constructor, or prototype key, that key is returned as an own-enumerable property; the recursive merge then resolves target['__proto__'] to Object.prototype and writes attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process. This issue is fixed in version 5.0.45.","severity":{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00389,"percentile":0.3345,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1321"],"published":"2026-07-14T19:40:05Z","modified":"2026-10-28T02:31:07Z","fixes":[{"ecosystem":"npm","package":"@feathersjs/commons","fixed_in":["5.0.45"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@feathersjs/commons","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"5.0.44"},{"fixed":"5.0.45"}]}]},{"source":"osv","ecosystem":"npm","package":"@feathersjs/commons","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"5.0.45"}]}]}],"products":[{"vendor":"feathersjs","product":"feathers"}],"references":[{"url":"https://github.com/feathersjs/feathers/security/advisories/GHSA-28xv-ph75-77wh","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/feathersjs/feathers/pull/3690","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/feathersjs/feathers/commit/28b3c03c63bdbff53115fdaa46c56980e7942acc","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/feathersjs/feathers/releases/tag/v5.0.45","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/advisories/GHSA-28xv-ph75-77wh"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54335.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-54335","tags":["advisory"]},{"url":"https://github.com/feathersjs/feathers","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-54335","title":"Feathersjs: Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__","description":"Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. In 5.0.44 and earlier, the _.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__, constructor, or prototype key, that key is returned as an own-enumerable property; the recursive merge then resolves target['__proto__'] to Object.prototype and writes attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process. This issue is fixed in version 5.0.45.","status":"published","published":"2026-07-17T20:56:51.857Z","modified":"2026-07-20T17:38:02.512Z","cvss":[{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low","assessor":"cna"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T13:38:09.774038Z"}],"euvd":[{"id":"EUVD-2026-45337","description":"Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. In 5.0.44 and earlier, the _.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__, constructor, or prototype key, that key is returned as an own-enumerable property; the recursive merge then resolves target['__proto__'] to Object.prototype and writes attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process. This issue is fixed in version 5.0.45.","status":"published","published":"2026-07-17T20:56:51Z","modified":"2026-07-20T17:38:02Z","cvss":[{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low"}],"updated_at":"2026-11-02T18:19:48.530346Z"}],"ghsa":[{"id":"GHSA-28xv-ph75-77wh","title":"Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__","description":"### 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).","status":"published","published":"2026-07-14T19:40:05Z","modified":"2026-07-14T19:40:06Z","cvss":[{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:40:43.958448Z"}],"nvd":[{"id":"CVE-2026-54335","description":"Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. In 5.0.44 and earlier, the _.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__, constructor, or prototype key, that key is returned as an own-enumerable property; the recursive merge then resolves target['__proto__'] to Object.prototype and writes attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process. This issue is fixed in version 5.0.45.","status":"published","published":"2026-07-17T22:17:44.84Z","modified":"2026-10-24T20:10:00.137Z","cvss":[{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low","assessor":"secondary"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:12:30.631352Z"}],"osv":[{"id":"CVE-2026-54335","title":"Feathersjs: Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__","description":"Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. In 5.0.44 and earlier, the _.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__, constructor, or prototype key, that key is returned as an own-enumerable property; the recursive merge then resolves target['__proto__'] to Object.prototype and writes attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process. This issue is fixed in version 5.0.45.","status":"published","published":"2026-07-17T20:56:51.857Z","modified":"2026-10-28T02:31:07.17830177Z","cvss":[{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:45:10.818486Z"},{"id":"GHSA-28xv-ph75-77wh","title":"Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__","description":"### 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).","status":"published","published":"2026-07-14T19:40:05Z","modified":"2026-07-14T19:56:45.565577Z","cvss":[{"version":"3.1","score":3.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"low"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:46:33.956911Z"}]}}