CVE-2025-66491 — Traefik has Inverted TLS Verification Logic in its ingress-nginx Provider
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 annotat…
Published: 2025-12-09 · CVSS: 5.9 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7