ELA-1651-1 modsecurity-crs security update

WAF bypass

2026-02-22
Packagemodsecurity-crs
Version3.2.3-0+deb10u4 (buster)
Related CVEs CVE-2023-38199


A issue has been fixed in modsecurity-crs, a set of generic attack detection rules for use with ModSecurity.

CVE-2023-38199

Coreruleset (aka OWASP ModSecurity Core Rule Set) through 3.3.4 does not detect multiple Content-Type request headers on some platforms. This might allow attackers to bypass a WAF with a crafted payload, aka “Content-Type confusion” between the WAF and the backend application. This occurs when the web application relies on only the last Content-Type header. Other platforms may reject the additional Content-Type header or merge conflicting headers, leading to detection as a malformed header.



For Debian 10 buster, these problems have been fixed in version 3.2.3-0+deb10u4.

We recommend that you upgrade your modsecurity-crs packages.

Further information about Extended LTS security advisories can be found in the dedicated section of our website.