CVE-2022-39955: Debian Linux

Critical severity, CVSS 9.8. EPSS: 1.4% chance of exploitation in the next 30 days.

The OWASP ModSecurity Core Rule Set (CRS) is affected by a partial rule set bypass by submitting a specially crafted HTTP Content-Type header field that indicates multiple character encoding schemes. A vulnerable back-end can potentially be exploited by declaring multiple Content-Type "charset" names and therefore bypassing the configurable CRS Content-Type header "charset" allow list. An encoded payload can bypass CRS detection this way and may then be decoded by the backend. The legacy CRS versions 3.0.x and 3.1.x are affected, as well as the currently supported versions 3.2.1 and 3.3.2. Integrators and users are advised to upgrade to 3.2.2 and 3.3.3 respectively.

Affected products

• Debian Debian Linux: version 10.0 only
• Fedoraproject Fedora: version 35 only; version 36 only; version 37 only
• Owasp Owasp Modsecurity Core Rule Set: from 3.0.0, before 3.2.2 (fixed in 3.2.2); from 3.3.0, before 3.3.3 (fixed in 3.3.3)

Published 2022-09-20. Last modified 2026-06-17.