ModSecurity before 2.5.11 treats request parameter values containing single quotes as files, which allows remote attackers to bypass filtering rules and perform other attacks such as cross-site scripting (XSS) attacks via a single quote in a request parameter in the Content-Disposition field of a request with a multipart/form-data Content-Type header.

ModSecurity before 2.6.6, when used with PHP, does not properly handle single quotes not at the beginning of a request parameter value in the Content-Disposition field of a request with a multipart/form-data Content-Type header, which allows remote attackers to bypass filtering rules and perform other attacks such as cross-site scripting (XSS) attacks. NOTE: this vulnerability exists because of an incomplete fix for CVE-2009-5031.

The mod_security2 module before 2.7.0 for the Apache HTTP Server allows remote attackers to bypass rules, and deliver arbitrary POST data to a PHP application, via a multipart request in which an invalid part precedes the crafted data.

ModSecurity before 2.7.3 allows remote attackers to read arbitrary files, send HTTP requests to intranet servers, or cause a denial of service (CPU and memory consumption) via an XML external entity declaration in conjunction with an entity reference, aka an XML External Entity (XXE) vulnerability.

apache2/modsecurity.c in ModSecurity before 2.7.6 allows remote attackers to bypass rules by using chunked transfer coding with a capitalized Chunked value in the Transfer-Encoding HTTP header.