Feathersjs: Prototype pollution in @feathersjs/commons _.merge via JSON-parsed __proto__
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| feathersjs | feathers | before 5.0.45 | 5.0.45 | Patch available | CNA |
| — | @feathersjs/commons (npm) | before 5.0.45 | 5.0.45 | Patch available | GHSA-28xv-ph75-77wh |
- feathers Vendorfeathersjs Affected before 5.0.45 Fixed in 5.0.45 Patch available CNA
- @feathersjs/commons (npm) Vendor— Affected before 5.0.45 Fixed in 5.0.45 Patch available GHSA-28xv-ph75-77wh
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:feathersjs:feathers:*:*:*:*:*:*:*:* | — | — | feathersjs |
- cpe:2.3:a:feathersjs:feathers:*:*:*:*:*:*:*:* Versions — — ·feathersjs
Remediation
- Fix · CNA feathers (feathersjs) Fixed in 5.0.45
- Fix · GHSA-28xv-ph75-77wh @feathersjs/commons (npm) Fixed in 5.0.45 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-54335
- 2026-10-03 Alias added: GHSA-28xv-ph75-77wh
References
Other 5
- https://github.com/feathersjs/feathers/security/advisories/GHSA-28xv-ph75-77wh
- https://github.com/feathersjs/feathers/pull/3690
- https://github.com/feathersjs/feathers/commit/28b3c03c63bdbff53115fdaa46c56980e7942acc
- https://github.com/feathersjs/feathers/releases/tag/v5.0.45
- https://github.com/feathersjs/feathers
More feathersjs vulnerabilities
- TI-2023-19332 feathersjs socket handler allows abusing implicit toString CVSS 3.1HIGH 7.5
- TI-2026-23379 NoSQL Injection via WebSocket id Parameter in MongoDB Adapter CVSS 4.0CRITICAL 9.3
- TI-2026-23378 Feathersjs has an OAuth Callback Account Takeover CVSS 4.0CRITICAL 9.3
- TI-2022-12183 Feathers - Query “__proto__” is converted to real prototype CVSS 3.1CRITICAL 10.0
- TI-2022-12182 Feathers - Improper parameter filtering in the Feathers js library, which may ultimately lead to SQL injection CVSS 3.1CRITICAL 10.0
- TI-2022-02237 Feathers - SQL injection via attribute aliases CVSS 3.1CRITICAL 10.0
Sources
- CVE-2026-54335 · CVE Program
- CVE-2026-54335 · NVD
- FIRST EPSS
- GHSA-28xv-ph75-77wh · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences