CVE-2026-53622
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.63%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 4.0
- 7.8 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.63% probability · 50th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-288, CWE-289
- Affected
- traefik/traefik
- Source
- security-advisories@github.com
EPSS 0.6% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://access.redhat.com/security/cve/CVE-2026-53622
- https://bugzilla.redhat.com/show_bug.cgi?id=2491924
- https://community.traefik.io/t/new-security-update-for-traefik-2-11-2-11-48-3-6-3-6-19-and-3-7-3-7-3/29917
- https://github.com/traefik/traefik/compare/v3.6.17...v3.6.18
- https://github.com/traefik/traefik/pull/13214
- https://github.com/traefik/traefik/releases/tag/v3.7.3Patch, Release Notes
- https://github.com/traefik/traefik/security/advisories/GHSA-9cr8-q42q-g8m7Exploit, Mitigation, Patch, Vendor Advisory
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53622.json
- https://access.redhat.com/errata/RHSA-2026:62260
- https://access.redhat.com/security/cve/CVE-2026-53622
- https://bugzilla.redhat.com/show_bug.cgi?id=2491924
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53622.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.