CVE-2025-55164: Helmetjs Content-Security-Policy-Parser

High severity, CVSS 8.8. EPSS: 0.4% chance of exploitation in the next 30 days.

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.

Affected products

• Helmetjs Content-Security-Policy-Parser: before 0.6.0 (fixed in 0.6.0)

Published 2025-08-12. Last modified 2026-06-17.