CVE-2026-53622

The record

Traefik is an HTTP reverse proxy and load balancer. Versions prior to 3.7.3, 3.6.18, and 2.11.51 have a critical vulnerability in Traefik's HTTP/3 (QUIC) TLS configuration selection that allows unauthenticated clients to bypass router-specific mTLS enforcement. When HTTP/3 is enabled on an entrypoint, the TLS handshake selects the applicable TLS configuration through an exact, case-sensitive lookup on the SNI value, which fails to match wildcard host patterns (e.g., *.example.com) or case variants of the configured hostname. Because the handshake falls back to the default TLS configuration — which may not require client certificates — a client can complete the QUIC handshake without presenting a certificate, while the subsequent HTTP routing layer still dispatches the request to a backend protected by a router-specific mTLS policy. The issue affects deployments where HTTP/3 is enabled, a router uses a wildcard Host rule or case-insensitive hostname matching, a router-specific TLSOptions enforces client certificate authentication, and UDP access to the entrypoint is reachable by an attacker. This vulnerability is fixed in versions 3.7.3, 3.6.18, and 2.11.51.

Affected packages

Related vulnerabilities

• CVE-2026-48491 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
• CVE-2026-48020 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
• CVE-2026-44774 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
• CVE-2026-41181 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
• CVE-2026-41174 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
• CVE-2026-41263 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
• CVE-2026-35051 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik
• CVE-2026-39858 Traefik is an HTTP reverse proxy and load balancer. Also affects traefik