OWASP ModSecurity

WAF bypass of the ModSecurity v3 release line

ModSecurity: Multipart form-data parser silently strips embedded line breaks from form-field values, enabling request-body inspection bypass

libModSecurity3 denial of service via segfault when using t:hexDecode on single-character query strings

ModSecurity: Unsigned integer underflow in @verifySSN / @verifyCPF / @verifySVNR operators

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

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.

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.

In ModSecurity before 2.9.6 and 3.x before 3.0.8, HTTP multipart requests were incorrectly parsed and could bypass the Web Application Firewall. NOTE: this is related to CVE-2022-39956 but can be considered independent changes to the ModSecurity (C language) codebase.

Trustwave ModSecurity 3.x before 3.0.10 has Inefficient Algorithmic Complexity.

ModSecurity has possible DoS vulnerability in sanitiseArg action

Trustwave ModSecurity 3.0.5 through 3.0.8 before 3.0.9 allows a denial of service (worker crash and unresponsiveness) because some inputs cause a segfault in the Transaction class for some configurations.

ModSecurity's Insufficient Return Value Handling can Lead to XSS and Source Code Disclosure

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

ModSecurity: Transformation utf8toUnicode produces wrong output on i386 architecture

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.