CVE-2026-53622
CriticalCVSS 10.0Exploitation Probability (EPSS)
Low risk15th percentile - higher than 15% of all known CVEs
Summary
In Traefik prior to 3.7.3, a critical vulnerability in HTTP/3 (QUIC) TLS configuration selection allows unauthenticated clients to bypass router-specific mTLS enforcement. The TLS handshake fails to match wildcard host patterns (e.g., *.example.com) or case variants, falling back to a default TLS config that may not require client certificates.
Risk Assessment
An attacker can access protected backends without presenting a required client certificate, violating mTLS security policies and potentially leading to unauthorized access to sensitive resources.
Recommendation
Upgrade Traefik to version 3.7.3 or later immediately. As a workaround, disable HTTP/3 on entrypoints where mTLS policies with wildcard rules are used.
Original NVD description (English source)
Traefik is an HTTP reverse proxy and load balancer. Prior to 3.7.3, there is 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 3.7.3.