GHSA-fh26-gfpp-7xxx: Traefik before v2.11.58 and v3.7.14 SNI Check Bypass via HTTP/2 Scheme
Traefik before v2.11.58 and v3.7.14 contains an authentication bypass vulnerability in its SNI check, which is skipped when request TLS state is nil. Unauthenticated clients can send HTTP/2 requests with the :scheme http pseudo-header over TLS on Go 1.27 builds to reach routers requiring client certificates without presenting one.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed to this bypass?
Affected deployments are Traefik versions before 2.11.58 or 3.7.14 running on Go 1.27 builds. The vulnerable path involves HTTP/2 traffic over TLS and routers configured to require client certificates.
What must an attacker do to exploit the issue?
An unauthenticated client must send an HTTP/2 request over TLS using the :scheme http pseudo-header. This causes the request TLS state to be nil, skipping Traefik's SNI check and allowing access to a router that requires a client certificate without presenting one.
Are routers that do not require client certificates affected by the described authentication bypass?
The described impact is access to routers requiring client certificates without providing one. The supplied information does not identify an equivalent bypass for routers that do not use client-certificate requirements.