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.
Metrics
Affected Vendors & Products
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References
History
Tue, 23 Jun 2026 22:15:00 +0000
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Tue, 23 Jun 2026 19:45:00 +0000
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| Description | 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. | |
| Title | Traefik: HTTP/3 mTLS bypass via exact SNI TLSOptions lookup for wildcard and mixed-case hosts | |
| Weaknesses | CWE-288 | |
| References |
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| Metrics |
cvssV4_0
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-06-23T19:13:28.844Z
Reserved: 2026-06-09T20:16:59.646Z
Link: CVE-2026-53622
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
Updated: 2026-06-23T22:00:08Z