Interpretation conflict in ModSecurity (mod_security) 2.1.0 and earlier allows remote attackers to bypass request rules via application/x-www-form-urlencoded POST data that contains an ASCIIZ (0x00) byte, which mod_security treats as a terminator even though it is still processed as normal data by some HTTP parsers including PHP 5.2.0, and possibly parsers in Perl, and Python.
https://exchange.xforce.ibmcloud.com/vulnerabilities/32872
http://www.vupen.com/english/advisories/2008/2115
http://www.vupen.com/english/advisories/2008/2109/references
http://www.vupen.com/english/advisories/2007/0868
http://www.securityfocus.com/bid/22831
http://www.oracle.com/technetwork/topics/security/cpujul2008-090335.html
http://www.modsecurity.org/blog/archives/2007/03/modsecurity_asc.html
http://www.gentoo.org/security/en/glsa/glsa-200705-17.xml
http://secunia.com/advisories/31113
http://secunia.com/advisories/31087
http://secunia.com/advisories/25316
http://secunia.com/advisories/24373
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c00727143