{"affected":[{"product":"ModSecurity","source":"CNA: GitHub_M","vendor":"owasp-modsecurity","versions":[{"status":"affected","version":"< 2.9.15"},{"status":"affected","version":">= 3.0.0, < 3.0.17"}]}],"cveId":"CVE-2026-104259","cwes":["CWE-670"],"description":"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.","epss":null,"exploits":[],"kev":null,"metrics":[{"score":5.4,"severity":"medium","source":"CNA: GitHub_M","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N","version":"3.1"}],"modifiedAt":1794260220048,"publishedAt":1794260220048,"references":[{"source":"CNA: GitHub_M","tags":["x_refsource_CONFIRM"],"url":"https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qrch-pjfr-9g47"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/owasp-modsecurity/ModSecurity/commit/264f348ae1823cb71cead3650b74c165678a1d46"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/owasp-modsecurity/ModSecurity/commit/49a65f471d3130b91f7fff9bfac9fe8dd9b97c44"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v2.9.15"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17"}],"remediation":[],"revision":"c56bfdbc74bfd2158e69ebd226b7b46f88843cdb5e43b09bb58d03d6a84b0441","sources":[{"modifiedAt":1794260220048,"name":"CNA: GitHub_M","retrievedAt":1794262104223,"url":"https://www.cve.org/CVERecord?id=CVE-2026-104259"}],"ssvc":null,"status":"published","title":"ModSecurity: removeComments Transformation Fails to Strip Adjacent Comments, Enabling WAF Rule Bypass","updatedAt":1794262104223}