Prototype Pollution in Feathersjs Feathers
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.
Vulnerability class: Prototype Pollution
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.7 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.004 (31.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 31st percentile — 31.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Feathersjs Feathers — versions < 5.0.45
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-54335?
- CVE-2026-54335 is a low-severity vulnerability in Feathersjs Feathers, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 3.7/10. Published 2026-07-17.
- How severe is CVE-2026-54335?
- Low severity. CVSS v3 base score is 3.7 out of 10.