GHSA-28XV-PH75-77WH
Vulnerability from github – Published: 2026-07-14 19:40 – Updated: 2026-07-14 19:40Impact
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__ (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.
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.
Patches
Fixed in @feathersjs/commons@5.0.45. The fix skips __proto__, constructor, and prototype keys during iteration — the standard remediation used by lodash and others.
Workarounds
Avoid passing JSON-parsed untrusted input through commons._.merge. Freezing Object.prototype or validating/sanitizing keys upstream also mitigates.
Credit
Reported responsibly by Andrew Ridings (@ridingsa).
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 5.0.44"
},
"package": {
"ecosystem": "npm",
"name": "@feathersjs/commons"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "5.0.45"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-54335"
],
"database_specific": {
"cwe_ids": [
"CWE-1321"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-14T19:40:05Z",
"nvd_published_at": null,
"severity": "LOW"
},
"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[\u0027__proto__\u0027]` 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 \u2014 trusted or untrusted \u2014 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 \u2014 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).",
"id": "GHSA-28xv-ph75-77wh",
"modified": "2026-07-14T19:40:05Z",
"published": "2026-07-14T19:40:05Z",
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
],
"summary": "Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__"
}
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