VYPR
Low severityNVD Advisory· Published Jul 17, 2026· Updated Jul 20, 2026

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

CVE-2026-54335

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 packages

Versions sourced from the GitHub Security Advisory.

PackageAffected versionsPatched versions
@feathersjs/commonsnpm
< 5.0.455.0.45

Affected products

1

Patches

Vulnerability mechanics

References

5

News mentions

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