Prototype Pollution in Helmetjs Content-Security-Policy-Parser
CVE-2025-55164
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.
Vulnerability class: Prototype Pollution
EPSS: 0.004 (34.8th percentile) — read the EPSS interpretation.
Affected products
- Helmetjs Content-security-policy-parser — versions < 0.6.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- af854a3a-2127-422b-91ae-364da2661108
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-55164?
- CVE-2025-55164 is a vulnerability in Helmetjs Content-Security-Policy-Parser, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). Published 2025-08-12.
- Is CVE-2025-55164 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.