CVE-2026-54335

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.

CVSS 3.1

3.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS

0.4% chance of exploitation in the next 30 days; higher than 32% of CVEs (scores of 2026-10-25)

CWE

CWE-1321

Published

2026-07-17

Modified

2026-10-24

Record from

the NVD, synced 2026-10-25

Packages (OSV)

References

• https://github.com/feathersjs/feathers/commit/28b3c03c63bdbff53115fdaa46c56980e7942acc
• https://github.com/feathersjs/feathers/pull/3690
• https://github.com/feathersjs/feathers/releases/tag/v5.0.45
• https://github.com/feathersjs/feathers/security/advisories/GHSA-28xv-ph75-77wh

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