Vulnerability in Owasp-Modsecurity Modsecurity
CVE-2026-104259
ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 2.9.15 and 3.0.17, msre_fn_removeComments_execute in apache2/re_tfns.c and inplace() in src/actions/transformations/remove_comments.cc implement t:removeComments by copying the character immediately after a comment terminator without re-evaluating it. Adjacent comments can therefore leave a later comment in the transformed value, allowing inline-comment obfuscation to bypass rules that depend on comment stripping. When a comment terminator is the final content, the same copy reads one byte beyond the input buffer. This issue is fixed in versions 2.9.15 and 3.0.17.
Published .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Owasp-Modsecurity Modsecurity — versions < 2.9.15, >= 3.0.0, < 3.0.17
Weakness classification (CWE)
References
- https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qrch-pjfr-9g47
- https://github.com/owasp-modsecurity/ModSecurity/commit/264f348ae1823cb71cead3650b74c165678a1d46
- https://github.com/owasp-modsecurity/ModSecurity/commit/49a65f471d3130b91f7fff9bfac9fe8dd9b97c44
- https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v2.9.15
- https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17
Frequently asked questions
- What is CVE-2026-104259?
- CVE-2026-104259 is a medium-severity vulnerability in Owasp-Modsecurity Modsecurity, classified under Always-Incorrect Control Flow Implementation. CVSS score: 5.4/10. Published 2026-11-09.
- How severe is CVE-2026-104259?
- Medium severity. CVSS v3 base score is 5.4 out of 10.