{"id":"CVE-2025-66491","url":"https://www.cyber-defence.io/tools/cve/CVE-2025-66491","generatedAt":"2026-10-28T07:26:01.173Z","title":"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.","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.","published":"2025-12-09T01:16:56.000Z","lastModified":"2026-10-14T22:10:00.000Z","status":"Analyzed","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":5.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"},"cwe":["CWE-295"],"affected":["traefik/traefik"],"epss":{"score":0.00221,"percentile":0.12554,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.22%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4","tags":["Patch"],"source":"security-advisories@github.com"},{"url":"https://github.com/traefik/traefik/releases/tag/v3.6.3","tags":["Release Notes"],"source":"security-advisories@github.com"},{"url":"https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vj","tags":["Patch","Vendor Advisory"],"source":"security-advisories@github.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-66491","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}