{"id":"CVE-2025-66491","sourceIdentifier":"security-advisories@github.com","published":"2025-12-09T01:16:55.720","lastModified":"2026-10-14T22:10:00.210","vulnStatus":"Analyzed","cveTags":[],"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."},{"lang":"es","value":"Traefik es un proxy inverso HTTP y un balanceador de carga. Las versiones 3.5.0 a 3.6.2 tienen la lógica de verificación TLS invertida en la anotación nginx.ingress.kubernetes.io/proxy-ssl-verify. Establecer la anotación en 'on' (con la intención de habilitar la verificación del certificado TLS del backend) en realidad deshabilita la verificación, permitiendo ataques man-in-the-middle contra backends HTTPS cuando los operadores creen que están protegidos. Este problema está solucionado en la versión 3.6.3."}],"affected":[{"source":"security-advisories@github.com","affectedData":[{"vendor":"traefik","product":"traefik","versions":[{"version":">= 3.5.0, < 3.6.3","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"security-advisories@github.com","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N","baseScore":5.9,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"NONE","availabilityImpact":"NONE"},"exploitabilityScore":2.2,"impactScore":3.6}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2025-12-09T14:17:29.439457Z","id":"CVE-2025-66491","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"security-advisories@github.com","type":"Secondary","description":[{"lang":"en","value":"CWE-295"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*","versionStartIncluding":"3.5.0","versionEndExcluding":"3.6.3","matchCriteriaId":"C2211A70-8944-46AA-B318-B3669174DBCE"}]}]}],"references":[{"url":"https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4","source":"security-advisories@github.com","tags":["Patch"]},{"url":"https://github.com/traefik/traefik/releases/tag/v3.6.3","source":"security-advisories@github.com","tags":["Release Notes"]},{"url":"https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vj","source":"security-advisories@github.com","tags":["Patch","Vendor Advisory"]}]}