{"id":"CVE-2026-73856","aliases":["DEBIAN-CVE-2026-73856","EUVD-2026-117554","GHSA-vmg8-j66p-vgvw","UBUNTU-CVE-2026-73856"],"status":"published","title":"ModSecurity: Response Body Inspection Bypass","description":"ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 until 3.0.17, src/transaction.cc compares a response Content-Type value against SecResponseBodyMimeType entries case-sensitively. A mixed-case response media type that is semantically equivalent to a configured lowercase type can therefore be treated as unconfigured, causing ModSecurity to skip RESPONSE_BODY inspection. An unauthenticated requester can then receive response content that a phase 4 rule would otherwise block, including sensitive error or debug data. This issue is fixed in version 3.0.17.","severity":{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00565,"percentile":0.47367,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-178"],"published":"2026-10-02T00:00:00Z","modified":"2026-11-10T10:00:11Z","affected":[{"source":"osv","ecosystem":"Debian:12","package":"modsecurity","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.10-1","3.0.11-1","3.0.12-1","3.0.12-1.1","3.0.12-1.1~exp1","3.0.13-1","3.0.14-1","3.0.15-1","3.0.16-1","3.0.9-1","3.0.9-1+deb12u1","3.0.9-1+deb12u2"]},{"source":"osv","ecosystem":"Debian:13","package":"modsecurity","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.14-1","3.0.14-1+deb13u1","3.0.14-1+deb13u2","3.0.15-1","3.0.16-1"]},{"source":"osv","ecosystem":"Debian:14","package":"modsecurity","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.14-1","3.0.15-1","3.0.16-1"]},{"source":"osv","ecosystem":"Ubuntu:20.04:LTS","package":"modsecurity","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.3-1","3.0.4-1","3.0.4-1build1"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"modsecurity","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.4-2","3.0.6-1"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"modsecurity","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.10-1","3.0.11-1","3.0.12-1","3.0.12-1.1build1","3.0.12-1.1build2"]},{"source":"osv","ecosystem":"Ubuntu:26.10","package":"modsecurity","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.14-1build2","3.0.15-1","3.0.16-1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"modsecurity","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3.0.14-1build1","3.0.14-1build2"]}],"products":[{"vendor":"owasp-modsecurity","product":"modsecurity"}],"references":[{"url":"https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-vmg8-j66p-vgvw","tags":["x_refsource_CONFIRM","exploit","advisory"]},{"url":"https://github.com/owasp-modsecurity/ModSecurity/commit/23ccd9202114f8313df3773f7992782fd9949c98","tags":["x_refsource_MISC","fix"]},{"url":"https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73856.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73856","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-73856","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-73856","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-73856","tags":["report"]},{"url":"https://github.com/advisories/GHSA-vmg8-j66p-vgvw","tags":["report"]},{"url":"https://modsecurity.org/20260928/security-update-digest-overview-of-recent-advisory-fixes-2026-september/","tags":["report"]}],"sources":{"cve":[{"id":"CVE-2026-73856","title":"ModSecurity: Response Body Inspection Bypass","description":"ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 until 3.0.17, src/transaction.cc compares a response Content-Type value against SecResponseBodyMimeType entries case-sensitively. A mixed-case response media type that is semantically equivalent to a configured lowercase type can therefore be treated as unconfigured, causing ModSecurity to skip RESPONSE_BODY inspection. An unauthenticated requester can then receive response content that a phase 4 rule would otherwise block, including sensitive error or debug data. This issue is fixed in version 3.0.17.","status":"published","published":"2026-11-05T15:50:09.778Z","modified":"2026-11-09T22:12:13.373Z","cvss":[{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-178"],"updated_at":"2026-11-09T23:35:22.059445Z"}],"euvd":[{"id":"EUVD-2026-117554","description":"ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 until 3.0.17, src/transaction.cc compares a response Content-Type value against SecResponseBodyMimeType entries case-sensitively. A mixed-case response media type that is semantically equivalent to a configured lowercase type can therefore be treated as unconfigured, causing ModSecurity to skip RESPONSE_BODY inspection. An unauthenticated requester can then receive response content that a phase 4 rule would otherwise block, including sensitive error or debug data. This issue is fixed in version 3.0.17.","status":"published","published":"2026-11-05T15:50:09Z","modified":"2026-11-09T22:12:13Z","cvss":[{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","level":"high"}],"updated_at":"2026-11-09T23:18:32.235826Z"}],"nvd":[{"id":"CVE-2026-73856","description":"ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 until 3.0.17, src/transaction.cc compares a response Content-Type value against SecResponseBodyMimeType entries case-sensitively. A mixed-case response media type that is semantically equivalent to a configured lowercase type can therefore be treated as unconfigured, causing ModSecurity to skip RESPONSE_BODY inspection. An unauthenticated requester can then receive response content that a phase 4 rule would otherwise block, including sensitive error or debug data. This issue is fixed in version 3.0.17.","status":"published","published":"2026-11-05T16:17:48.443Z","modified":"2026-11-09T23:17:25.853Z","cvss":[{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-178"],"updated_at":"2026-11-10T02:16:32.753769Z"}],"osv":[{"id":"CVE-2026-73856","title":"ModSecurity: Response Body Inspection Bypass","description":"ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 until 3.0.17, src/transaction.cc compares a response Content-Type value against SecResponseBodyMimeType entries case-sensitively. A mixed-case response media type that is semantically equivalent to a configured lowercase type can therefore be treated as unconfigured, causing ModSecurity to skip RESPONSE_BODY inspection. An unauthenticated requester can then receive response content that a phase 4 rule would otherwise block, including sensitive error or debug data. This issue is fixed in version 3.0.17.","status":"published","published":"2026-11-05T15:50:09.778Z","modified":"2026-11-11T07:24:30.28389823Z","cvss":[{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","level":"high"}],"cwes":["CWE-178"],"updated_at":"2026-11-07T03:08:10.099944Z"},{"id":"DEBIAN-CVE-2026-73856","description":"ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 until 3.0.17, src/transaction.cc compares a response Content-Type value against SecResponseBodyMimeType entries case-sensitively. A mixed-case response media type that is semantically equivalent to a configured lowercase type can therefore be treated as unconfigured, causing ModSecurity to skip RESPONSE_BODY inspection. An unauthenticated requester can then receive response content that a phase 4 rule would otherwise block, including sensitive error or debug data. This issue is fixed in version 3.0.17.","status":"published","published":"2026-11-05T16:17:48.443Z","modified":"2026-11-10T10:00:11.49448293Z","cvss":[{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","level":"high"}],"updated_at":"2026-11-10T10:26:30.347596Z"},{"id":"UBUNTU-CVE-2026-73856","description":"[GHSA-vmg8-j66p-vgvw: Response body inspection bypass via non-canonical Content-Type casing]","status":"published","published":"2026-10-02T00:00:00Z","modified":"2026-11-07T01:46:43.236118292Z","cvss":[{"version":"3.1","score":8.6,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N","level":"high"}],"updated_at":"2026-11-07T01:56:47.245871Z"}]}}