{"schema_version":"1.9.0","id":"CVE-2025-66491","published":"2025-12-09T00:38:39.208Z","modified":"2026-08-12T03:51:21.911225470Z","aliases":["GHSA-7vww-mvcr-x6vj","GO-2025-4205"],"related":["CGA-6h5r-m494-hr3j","SUSE-SU-2026:0037-1","openSUSE-SU-2026:10020-1","openSUSE-SU-2026:21483-1"],"summary":"Traefik has Inverted TLS Verification Logic in its ingress-nginx Provider","details":"Traefik is an HTTP reverse proxy and load balancer. Versions 3.5.0 through 3.6.2 have inverted TLS verification logic in the nginx.ingress.kubernetes.io/proxy-ssl-verify annotation. Setting the annotation to \"on\" (intending to enable backend TLS certificate verification) actually disables verification, allowing man-in-the-middle attacks against HTTPS backends when operators believe they are protected. This issue is fixed in version 3.6.3.","affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/traefik/traefik","events":[{"introduced":"2cbd96e64c929bea8f933efa75080e9656314f34"},{"fixed":"8a621274b81cd177ea5f6e07a5d5472af7d213b3"},{"fixed":"14a1aedf5704673d875d210d7bacf103a43c77e4"}],"database_specific":{"cpe":"cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"3.5.0"},{"fixed":"3.6.3"}],"source":["CPE_RANGE","REFERENCES"]}}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-66491.json"}}],"references":[{"type":"WEB","url":"https://github.com/traefik/traefik/releases/tag/v3.6.3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66491.json"},{"type":"ADVISORY","url":"https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-66491"},{"type":"FIX","url":"https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4"}],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-295"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66491.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"}]}