ModSecurity 3.x through 3.0.5 mishandles excessively nested JSON objects. Crafted JSON objects with nesting tens-of-thousands deep could result in the web server being unable to service legitimate requests. Even a moderately large (e.g., 300KB) HTTP request can occupy one of the limited NGINX worker processes for minutes and consume almost all of the available CPU on the machine. Modsecurity 2 is similarly vulnerable: the affected versions include 2.8.0 through 2.9.4.

OWASP ModSecurity Core Rule Set 3.1.x before 3.1.2, 3.2.x before 3.2.1, and 3.3.x before 3.3.2 is affected by a Request Body Bypass via a trailing pathname.

ModSecurity 3.x before 3.0.4 mishandles key-value pair parsing, as demonstrated by a "string index out of range" error and worker-process crash for a "Cookie: =abc" header.

Trustwave ModSecurity 3.x through 3.0.4 allows denial of service via a special request. NOTE: The discoverer reports "Trustwave has signaled they are disputing our claims." The CVE suggests that there is a security issue with how ModSecurity handles regular expressions that can result in a Denial of Service condition. The vendor does not consider this as a security issue because1) there is no default configuration issue here. An attacker would need to know that a rule using a potentially problematic regular expression was in place, 2) the attacker would need to know the basic nature of the regular expression itself to exploit any resource issues. It's well known that regular expression usage can be taxing on system resources regardless of the use case. It is up to the administrator to decide on when it is appropriate to trade resources for potential security benefit

An issue was discovered in OWASP ModSecurity Core Rule Set (CRS) 3.0.2. Use of X.Filename instead of X_Filename can bypass some PHP Script Uploads rules, because PHP automatically transforms dots into underscores in certain contexts where dots are invalid.

An issue was discovered in OWASP ModSecurity Core Rule Set (CRS) through 3.1.0. /rules/REQUEST-933-APPLICATION-ATTACK-PHP.conf allows remote attackers to cause a denial of service (ReDOS) by entering a specially crafted string with set_error_handler# at the beginning and nested repetition operators. NOTE: the software maintainer disputes that this is a vulnerability because the issue cannot be exploited via ModSecurity

An issue was discovered in OWASP ModSecurity Core Rule Set (CRS) through 3.1.0. /rules/REQUEST-933-APPLICATION-ATTACK-PHP.conf allows remote attackers to cause a denial of service (ReDOS) by entering a specially crafted string with next# at the beginning and nested repetition operators. NOTE: the software maintainer disputes that this is a vulnerability because the issue cannot be exploited via ModSecurity

An issue was discovered in OWASP ModSecurity Core Rule Set (CRS) through 3.1.0. /rules/REQUEST-933-APPLICATION-ATTACK-PHP.conf allows remote attackers to cause a denial of service (ReDOS) by entering a specially crafted string with $a# at the beginning and nested repetition operators. NOTE: the software maintainer disputes that this is a vulnerability because the issue cannot be exploited via ModSecurity

An issue was discovered in OWASP ModSecurity Core Rule Set (CRS) through 3.1.0. /rules/REQUEST-942-APPLICATION-ATTACK-SQLI.conf allows remote attackers to cause a denial of service (ReDOS) by entering a specially crafted string with nested repetition operators.

An issue was discovered in OWASP ModSecurity Core Rule Set (CRS) through 3.1.0. /rules/REQUEST-932-APPLICATION-ATTACK-RCE.conf allows remote attackers to cause a denial of service (ReDOS) by entering a specially crafted string with nested repetition operators. NOTE: the software maintainer disputes that this is a vulnerability because the issue cannot be exploited via ModSecurity