What’s Vulnerable › Vulnerabilities

CVE-2026-54335: Feathersjs: Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__

• Severity: low (CVSS 3.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-17 · updated 2026-10-24
• Weakness: CWE-1321

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.

Affected products

• feathersjs feathers: before 5.0.45

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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