Prototype pollution via unsafe recursive merge
Published Jul 17, 2026 · Updated Jul 17, 2026
Prototype pollution in @feathersjs/commons 4.0.0 through 4.5.19 and 5.0.0 through 5.0.44 allows remote attackers to modify object state. The _.merge(target, source) utility recursively follows own-enumerable proto, constructor, or prototype keys from JSON-parsed input and writes attacker-supplied properties onto Object.prototype. Exploitation requires a downstream plugin or application to pass attacker-controlled parsed JSON to this utility; first-party Feathers packages do not, and successful pollution persists for the Node process lifetime.
Summary
What happened
Prototype pollution in @feathersjs/commons 4.0.0 through 4.5.19 and 5.0.0 through 5.0.44 allows remote attackers to modify object state. The _.merge(target, source) utility recursively follows own-enumerable proto, constructor, or prototype keys from JSON-parsed input and writes attacker-supplied properties onto Object.prototype. Exploitation requires a downstream plugin or application to pass attacker-controlled parsed JSON to this utility; first-party Feathers packages do not, and successful pollution persists for the Node process lifetime.
The record
- CVE
- CVE-2026-54335
- Published
- Jul 17, 2026
- Updated
- Jul 17, 2026
- Vendor
- FeathersJS
- Product
- Feathers
- Classifications
- CWE-1321, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 17, 2026CVE publishedPublication date reported by the CVE source.
- Jul 17, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 5.0.45
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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