Trustwave ModSecurity 3.0.0 through 3.0.3 allows an attacker to send crafted requests that may, when sent quickly in large volumes, lead to the server becoming slow or unresponsive (Denial of Service) because of a flaw in Transaction::addRequestHeader in transaction.cc.

A SQL injection bypass (aka PL1 bypass) exists in OWASP ModSecurity Core Rule Set (owasp-modsecurity-crs) through v3.1.0-rc3 via {`a`b} where a is a special function name (such as "if") and b is the SQL statement to be executed.

ModSecurity 3.0.0 has XSS via an onerror attribute of an IMG element. NOTE: a third party has disputed this issue because it may only apply to environments without a Core Rule Set configured

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.

The ModSecurity module before 2.7.4 for the Apache HTTP Server allows remote attackers to cause a denial of service (NULL pointer dereference, process crash, and disk consumption) via a POST request with a large body and a crafted Content-Type header.

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.

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 2.5.11 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 PDF XSS protection feature in ModSecurity before 2.5.8 allows remote attackers to cause a denial of service (Apache httpd crash) via a request for a PDF file that does not use the GET method.