Martin Holst Swende discovered a flaw in the way chunked requests are handled in ModSecurity, an Apache module whose purpose is to tighten the Web application security. A remote attacker could use this flaw to bypass intended mod_security restrictions by using chunked transfer coding with a capitalized Chunked value in the Transfer-Encoding HTTP header, allowing to send requests containing content that should have been removed by mod_security.

For the stable distribution (wheezy), this problem has been fixed in version 2.6.6-6+deb7u2. For the testing distribution (jessie), this problem has been fixed in version 2.7.7-1. For the unstable distribution (sid), this problem has been fixed in version 2.7.7-1. We recommend that you upgrade your modsecurity-apache packages.

modsecurity-apache on Debian Linux

This check tests the installed software version using the apt package manager.

• http://www.debian.org/security/2014/dsa-2991.html

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Updated on 2015-03-25