OWASP ModSecurity CRS multipart bypass (v3.0.x-3.3.2) upgrade to 3.2.2/3.3.3
CVE-2022-39956 Published on September 20, 2022
Partial rule set bypass in OWASP ModSecurity Core Rule Set for HTTP multipart requests using character encoding in the Content-Type or Content-Transfer-Encoding header
The OWASP ModSecurity Core Rule Set (CRS) is affected by a partial rule set bypass for HTTP multipart requests by submitting a payload that uses a character encoding scheme via the Content-Type or the deprecated Content-Transfer-Encoding multipart MIME header fields that will not be decoded and inspected by the web application firewall engine and the rule set. The multipart payload will therefore bypass detection. A vulnerable backend that supports these encoding schemes can potentially be exploited. The legacy CRS versions 3.0.x and 3.1.x are affected, as well as the currently supported versions 3.2.1 and 3.3.2. Integrators and users are advised upgrade to 3.2.2 and 3.3.3 respectively. The mitigation against these vulnerabilities depends on the installation of the latest ModSecurity version (v2.9.6 / v3.0.8).
Vulnerability Analysis
CVE-2022-39956 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be low. considered to have a small impact on confidentiality and integrity and availability.
Weakness Type
What is an AuthZ Vulnerability?
The software performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
CVE-2022-39956 has been classified to as an AuthZ vulnerability or weakness.
Products Associated with CVE-2022-39956
You can be notified by email with stack.watch whenever vulnerabilities like CVE-2022-39956 are published in these products:
Affected Versions
OWASP ModSecurity Core Rule Set:- Version 3.0.x is affected.
- Version 3.1.x is affected.
- Version unspecified, <= 3.2.1 is affected.
- Version unspecified, <= 3.3.2 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.