CVE-2022-39956: Debian Linux

Critical severity, CVSS 9.8. EPSS: 1.2% chance of exploitation in the next 30 days.

The OWASP ModSecurity Core Rule Set (CRS) is affected by a partial rule set bypass for HTTP multipart requests by submitting a payload that uses a character encoding scheme via the Content-Type or the deprecated Content-Transfer-Encoding multipart MIME header fields that will not be decoded and inspected by the web application firewall engine and the rule set. The multipart payload will therefore bypass detection. A vulnerable backend that supports these encoding schemes can potentially be exploited. 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 upgrade to 3.2.2 and 3.3.3 respectively. The mitigation against these vulnerabilities depends on the installation of the latest ModSecurity version (v2.9.6 / v3.0.8).

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.