CVE-2022-39955
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.42%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 1.42% probability · 73th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-863
- Affected
- owasp/owasp modsecurity core rule set · fedoraproject/fedora · debian/debian linux
- Source
- vulnerability@ncsc.ch
EPSS 1.4% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://coreruleset.org/20220919/crs-version-3-3-3-and-3-2-2-covering-several-cves/Patch, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2023/01/msg00033.htmlMailing List, Third Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HL2L2GF7GOCWPMJZDUE5OXDSXHGG3XUJ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PD56EAYNGB6E6QQH62LAYCONOP6OH5DZ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YPQ6CCMX3MU4A7MTCGQJA7VMJW3IQDXV/
- https://security.gentoo.org/glsa/202305-25
- https://coreruleset.org/20220919/crs-version-3-3-3-and-3-2-2-covering-several-cves/Patch, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2023/01/msg00033.htmlMailing List, Third Party Advisory
- https://lists.debian.org/debian-lts-announce/2025/08/msg00004.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HL2L2GF7GOCWPMJZDUE5OXDSXHGG3XUJ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PD56EAYNGB6E6QQH62LAYCONOP6OH5DZ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YPQ6CCMX3MU4A7MTCGQJA7VMJW3IQDXV/
- https://security.gentoo.org/glsa/202305-25
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.