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.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2026-53622)

ID	Name	Product	Family	Type	Severity
443320	SCA: security update for Traefik (GHSA-9cr8-q42q-g8m7)	Tenable Cloud Security	SCA Checks	Local	high
443320	SCA: security update for Traefik (GHSA-9cr8-q42q-g8m7)	Tenable Self-Hosted Container Security	SCA Checks	Local	high

Detections

Analytics

CVE-2026-53622

high

Tenable Plugins

high

high