title: Partial rule set bypass in OWASP ModSecurity Core Rule Set by submitting a specially crafted HTTP Content-Type header
description: 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.
problem types: CWE-863  Incorrect Authorization
affected:
{
vendor: OWASP
product: ModSecurity Core Rule Set
versions:
version: 3.0.x, status: affected
version: 3.1.x, status: affected
version: unspecified, lessThanOrEqual: 3.2.1, status: affected, versionType: custom
version: unspecified, lessThanOrEqual: 3.3.2, status: affected, versionType: custom
}
metrics:
cvssV3_1: [
version: 3.1
vectorString: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
attackVector: NETWORK
attackComplexity: LOW
privilegesRequired: NONE
userInteraction: NONE
scope: UNCHANGED
confidentialityImpact: LOW
integrityImpact: LOW
availabilityImpact: LOW
baseScore: 7.3
baseSeverity: HIGH
]
solutions: upgrade to 3.2.2 or 3.3.3