Auth bypass in Owasp Modsecurity Core Rule Set
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. 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.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.014 (72.8th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 73rd percentile — 72.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.014 · newest: 0.014 · change: +0.000
Affected products
- Owasp Modsecurity Core Rule Set — versions 3.0.x, 3.1.x, unspecified
- Owasp Modsecurity Core Rule Set
- Debian Linux — versions 10.0
- Fedoraproject Fedora — versions 35, 36, 37
Weakness classification (CWE)
Public proof-of-concept exploits
References
- coreruleset.org/20220919/crs-version-3-3-3-and-3-2-2-covering-several-cves/ (Patch, Vendor Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.debian.org/debian-lts-announce/2023/01/msg00033.html (mailing-list, Mailing List, Third Party Advisory)
- security.gentoo.org/glsa/202305-25 (vendor-advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2022-39955?
- CVE-2022-39955 is a high-severity vulnerability in Owasp Modsecurity Core Rule Set, classified under Incorrect Authorization. CVSS score: 7.3/10. Published 2022-09-20.
- How severe is CVE-2022-39955?
- High severity. CVSS v3 base score is 7.3 out of 10.
- Is CVE-2022-39955 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.