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

CVE ID :CVE-2026-54335

Published : July 17, 2026, 10:17 p.m. | 1 hour, 20 minutes ago

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: 3.7 | LOW

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