critical
9.8
CWE
863
Advisory Published
Updated

CVE-2022-39955: Partial rule set bypass in OWASP ModSecurity Core Rule Set by submitting a specially crafted HTTP Content-Type header

First published: Tue Sep 20 2022(Updated: )

The OWASP ModSecurity Core Rule Set (CRS) is affected by a partial rule set bypass by submitting a specially crafted HTTP Content-Type header field that indicates multiple character encoding schemes. A vulnerable back-end can potentially be exploited by declaring multiple Content-Type "charset" names and therefore bypassing the configurable CRS Content-Type header "charset" allow list. An encoded payload can bypass CRS detection this way and may then be decoded by the backend. 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 to upgrade to 3.2.2 and 3.3.3 respectively.

Credit: vulnerability@ncsc.ch

Affected SoftwareAffected VersionHow to fix
Owasp Owasp Modsecurity Core Rule Set>=3.0.0<3.2.2
Owasp Owasp Modsecurity Core Rule Set>=3.3.0<3.3.3
Fedoraproject Fedora=35
Fedoraproject Fedora=36
Fedoraproject Fedora=37
Debian Debian Linux=10.0

Remedy

https://coreruleset.org/20220919/crs-version-3-3-3-and-3-2-2-covering-several-cves/

Remedy

upgrade to 3.2.2 or 3.3.3

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Reference Links

Frequently Asked Questions

  • What is the vulnerability ID for the OWASP ModSecurity Core Rule Set bypass vulnerability?

    The vulnerability ID for the OWASP ModSecurity Core Rule Set bypass vulnerability is CVE-2022-39955.

  • What is the severity of CVE-2022-39955?

    CVE-2022-39955 has a severity level of 9.8 (critical).

  • How does the OWASP ModSecurity Core Rule Set bypass vulnerability work?

    The vulnerability allows an attacker to bypass certain rules in the OWASP ModSecurity Core Rule Set by manipulating the HTTP Content-Type header.

  • Which versions of the OWASP ModSecurity Core Rule Set are affected by CVE-2022-39955?

    Versions 3.0.0 to 3.2.2 and versions 3.3.0 to 3.3.3 of the OWASP ModSecurity Core Rule Set are affected by CVE-2022-39955.

  • Are there any references for CVE-2022-39955?

    Yes, you can find more information about CVE-2022-39955 at: [Reference 1](https://coreruleset.org/20220919/crs-version-3-3-3-and-3-2-2-covering-several-cves/), [Reference 2](https://lists.debian.org/debian-lts-announce/2023/01/msg00033.html), [Reference 3](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/HL2L2GF7GOCWPMJZDUE5OXDSXHGG3XUJ/)

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