{"id":"CVE-2025-66491","state":"PUBLISHED","title":"Traefik has Inverted TLS Verification Logic in its ingress-nginx Provider","description":"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.","publishedAt":"2025-12-09T00:38:39.208Z","updatedAt":"2025-12-09T16:03:28.511Z","severity":{"score":5.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["traefik traefik"],"affected":[{"vendor":"traefik","product":"traefik","versions":[{"version":">= 3.5.0, < 3.6.3","status":"affected"}]}],"references":["https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vj","https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4","https://github.com/traefik/traefik/releases/tag/v3.6.3"],"weaknesses":["CWE-295"],"ingestedAt":"2026-10-29T20:09:56.034Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/66xxx/CVE-2025-66491.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-66491","state":"PUBLISHED","datePublished":"2025-12-09T00:38:39.208Z","dateUpdated":"2025-12-09T16:03:28.511Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2025-12-02T22:44:04.707Z"},"containers":{"cna":{"title":"Traefik has Inverted TLS Verification Logic in its ingress-nginx Provider","descriptions":[{"lang":"en","value":"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":[{"vendor":"traefik","product":"traefik","versions":[{"version":">= 3.5.0, < 3.6.3","status":"affected"}]}],"references":[{"url":"https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vj","name":"https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vj","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4","name":"https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4","tags":["x_refsource_MISC"]},{"url":"https://github.com/traefik/traefik/releases/tag/v3.6.3","name":"https://github.com/traefik/traefik/releases/tag/v3.6.3","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.9,"baseSeverity":"MEDIUM","confidentialityImpact":"HIGH","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-295","lang":"en","description":"CWE-295: Improper Certificate Validation","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2025-12-09T00:38:39.208Z"},"source":{"advisory":"GHSA-7vww-mvcr-x6vj","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-12-09T14:17:29.439457Z","id":"CVE-2025-66491","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-12-09T16:03:28.511Z"}}]}}}