CVE-2025-66491
MEDIUM severity · CVSS 5.9 · CWE-295
5.9CVSS MEDIUM
Summary
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.
Impact & exploitability
Attack vectorNetwork
Attack complexityHigh
Privileges requiredNone
User interactionNone
Confidentiality impactHigh
Integrity impactNone
Availability impactNone
Exploit probability (EPSS)0%
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected products we track (1)
Recommendation
Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.
Official patch: https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4 ↗