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Vulnerability · Published Sep 20, 2022 · Assigned by NCSC.ch

CVE-2022-39957Response body bypass in OWASP ModSecurity Core Rule Set via a specialy crafted charset in the HTTP Accept header

High 7.3

In plain English

A high-severity security flaw in ModSecurity Core Rule Set from OWASP. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.0% (higher than 63% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.3High
Exploit odds (30 days)1.0%top 37.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

The OWASP ModSecurity Core Rule Set (CRS) is affected by a response body bypass. A client can issue an HTTP Accept header field containing an optional "charset" parameter in order to receive the response in an encoded form. Depending on the "charset", this response can not be decoded by the web application firewall. A restricted resource, access to which would ordinarily be detected, may therefore bypass detection. 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12modsecurity-crs3.3.4-1DEBIAN-CVE-2022-39957
Debian:13modsecurity-crs3.3.4-1DEBIAN-CVE-2022-39957
Debian:14modsecurity-crs3.3.4-1DEBIAN-CVE-2022-39957
Ubuntu:22.04:LTSmodsecurity-crsno fix listedUBUNTU-CVE-2022-39957
Ubuntu:24.04:LTSmodsecurity-crsno fix listedUBUNTU-CVE-2022-39957
Ubuntu:25.10modsecurity-crsno fix listedUBUNTU-CVE-2022-39957
Ubuntu:26.04:LTSmodsecurity-crsno fix listedUBUNTU-CVE-2022-39957
Ubuntu:26.10modsecurity-crsno fix listedUBUNTU-CVE-2022-39957

Affected products (as reported)

VendorProductVersions
OWASP ModSecurity Core Rule Set 3.0.x3.1.xunspecified – through 3.2.1unspecified – through 3.3.2

Weakness: CWE-693 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

References