CVE-2025-66491

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.

• CWE-295

• https://github.com/traefik/traefik/commit/14a1aedf5704673d875d210d7bacf103a43c77e4Patch
• https://github.com/traefik/traefik/releases/tag/v3.6.3Release Notes
• https://github.com/traefik/traefik/security/advisories/GHSA-7vww-mvcr-x6vjPatch, Vendor Advisory

Published

Dec 9, 2025

Last Modified

Jun 17, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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