content-security-policy-parser Prototype Pollution Vulnerability May Lead to RCE
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.
Summary
content-security-policy-parser parses content security policy directives. A prototype pollution vulnerability exists in versions 0.5.0 and earlier, wherein if a policy name is called __proto__, one can override the Object prototype. This issue has been patched in version 0.6.0. A workaround involves disabling prototype method in NodeJS, neutralizing all possible prototype pollution attacks. Provide either --disable-proto=delete (recommended) or --disable-proto=throw as an argument to node to enable this feature.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- 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 |
|---|---|---|---|---|---|
| helmetjs | content-security-policy-parser | before 0.6.0 | 0.6.0 | Patch available | CNA |
| — | content-security-policy-parser (npm) | before 0.6.0 | 0.6.0 | Patch available | GHSA-w2cq-g8g3-gm83 |
- content-security-policy-parser Vendorhelmetjs Affected before 0.6.0 Fixed in 0.6.0 Patch available CNA
- content-security-policy-parser (npm) Vendor— Affected before 0.6.0 Fixed in 0.6.0 Patch available GHSA-w2cq-g8g3-gm83
Remediation
- Fix · CNA content-security-policy-parser (helmetjs) Fixed in 0.6.0
- Fix · GHSA-w2cq-g8g3-gm83 content-security-policy-parser (npm) Fixed in 0.6.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2025-55164
- 2026-10-03 Alias added: GHSA-w2cq-g8g3-gm83
References
Other 4
- https://github.com/helmetjs/content-security-policy-parser/security/advisories/GHSA-w2cq-g8g3-gm83
- https://github.com/helmetjs/content-security-policy-parser/issues/11
- https://github.com/helmetjs/content-security-policy-parser/commit/b13a52554f0168af393e3e38ed4a94e9e6aea9dc
- https://github.com/helmetjs/content-security-policy-parser
Sources
- CVE-2025-55164 · CVE Program
- CVE-2025-55164 · NVD
- FIRST EPSS
- GHSA-w2cq-g8g3-gm83 · 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