Low, CVSS 3.7npmAmendedPublished
Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__
CVE-2026-54335 · GHSA-28xv-ph75-77wh
- Affected
- npm @feathersjs/commons <= 5.0.44
- Fixed in
- 5.0.45· Vendor fix available
- Issue
- Impact 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 (or constructor / prototype) key, that key is returned as an own-enumerable property. The recursive merge then resolves target['proto'] to Object.prototype and writes the attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process. Scope of real-world risk is limited. No first-party Feathers package routes input — trusted or untrusted — through commons..merge. The @feathersjs/authentication package, which does merge request-influenced data, uses lodash/merge (prototype-pollution-safe since 4.17.12), not this utility. Exploitation therefore requires a downstream plugin or application to pass JSON-parsed, attacker-controlled input directly through the exported .merge. Patches Fixed in…
Recommended action: Upgrade to 5.0.45 or later, then redeploy and verify.A vendor fix does not resolve your finding until you verify it in your own systems.