Traefik versions >= v3.7.0 and <= v3.7.10 contain an authentication bypass in the Kubernetes Ingress NGINX provider. The TLS option generated for an Ingress carrying the nginx.ingress.kubernetes.io/auth-tls-secret annotation was named after the Ingress namespace and name. As a result, two Ingress objects sharing the same host, the same client CA secret, and the same client-authentication mode produced two distinct TLS option names for that host. Traefik treats this as a TLS options conflict and falls back to the entry point's default TLS configuration, which does not request a client certificate, so a route configured with nginx.ingress.kubernetes.io/auth-tls-verify-client: "on" becomes reachable without a client certificate. Only the v3.7 line is affected; the issue is fixed in v3.7.11.

Traefik versions before v2.11.55 contain an authentication bypass vulnerability in the digestAuth middleware where unknown usernames receive an empty secret instead of rejection. Attackers can compute a valid digest response using the empty secret and arbitrary credentials to bypass authentication on any digestAuth-protected route without a valid username or password.

Traefik versions from v3.7.1 fail to enforce crossProviderNamespaces restrictions on the traefik.ingress.kubernetes.io/service.middlewares Service annotation in the Kubernetes Ingress provider. A namespace-limited tenant excluded from the allowlist can attach an operator-owned middleware to its Service, and if that middleware injects backend credentials, recover them at a controlled backend.

Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.53, 3.6.24, and 3.7.9, Traefik's default HTTP reverse proxy forwards a plain HTTP/2 or HTTP/3 CONNECT request and its body to an HTTP/1.1 upstream through a shared net/http.Transport. When the upstream answers the CONNECT with a keep-alive non-2xx response and does not drain the body, Traefik returns the desynchronized backend socket to its shared pool and reuses it for other clients. An unauthenticated attacker can use this behavior to make a different client read the attacker's smuggled response, which can include authenticated or private content from another request. The ForwardAuth middleware with forwardBody true and preserveRequestMethod true can re-issue a CONNECT with the buffered body attached, exposing the auth-client pool to the same desynchronization. This issue is fixed in 2.11.53, 3.6.24, and 3.7.9.

Traefik is an open-source edge router that makes publishing services a fun and easy experience. Prior to 2.11.54, 3.6.25, and 3.7.10, cross-namespace @kubernetescrd references are not rejected for TraefikService backend references resolved by the service resolver. A tenant confined by RBAC to a single namespace can therefore bind its own router to a TraefikService owned by another namespace and expose or reroute that namespace's backend, defeating the namespace isolation allowCrossNamespace=false is meant to enforce. This issue is fixed in version 2.11.54, 3.6.25, 3.7.10.

Traefik is an open source HTTP reverse proxy and load balancer. From 3.6.11 until 3.6.25 and 3.7.10, Traefik's BasicAuth middleware in pkg/middlewares/auth/basic_auth.go deduplicates concurrent password checks with a singleflight key built from the delimiter-free concatenation of password and secret, allowing an attacker who has a valid credential and the stored hash to authenticate as an unconfigured username when headerField trusts the forwarded identity. This issue is fixed in 3.6.25 and 3.7.10.

Traefik is an open source HTTP reverse proxy and load balancer. From 3.0.0 until 3.6.25 and 3.7.10, Traefik's Kubernetes Gateway API provider in pkg/provider/kubernetes/gateway/httproute.go, grpcroute.go, tcproute.go, and tlsroute.go builds HTTPRoute, GRPCRoute, TCPRoute, and TLSRoute router and service identities by hyphen-concatenating namespace, route name, Gateway identity, entry point, and rule index, allowing colliding Routes to overwrite another namespace's backend. This issue is fixed in 3.6.25 and 3.7.10.

Traefik versions >= v3.7.0 and <= v3.7.7 contain a path traversal vulnerability in the Kubernetes Ingress NGINX provider's RewriteTarget middleware (generated from the nginx.ingress.kubernetes.io/rewrite-target annotation). When an Ingress path uses a regex that captures attacker-controlled text without requiring a path separator (e.g., path /api(.*) with rewrite target /$1), a crafted request such as /api../admin matches the public router, is rewritten to a dot-segment traversal path (/../admin), and is forwarded without post-replacement normalization validation. A backend that normalizes dot segments resolves the path to a protected endpoint (e.g., /admin) reachable only through a separate router secured with BasicAuth, DigestAuth, or ForwardAuth, resulting in route-level authentication bypass. The issue is fixed in v3.7.8.

Traefik 3.6.0 through 3.6.22 and 3.7.0 through 3.7.6 fail to enforce the crossProviderNamespaces allowlist for IngressRouteTCP service serversTransport references (the allowlist was only enforced for HTTP serversTransport references). A low-privileged Kubernetes user in a namespace not listed in crossProviderNamespaces can set serversTransport: foo@file on an IngressRouteTCP service, causing Traefik to accept the forbidden cross-provider reference and use a file-provider TCPServersTransport — including privileged backend mTLS client certificates, SPIFFE identity, or PROXY-protocol settings. This is fixed in 3.6.23 and 3.7.7.

Traefik versions 3.7.0 through 3.7.6 contain a namespace confusion vulnerability in the Kubernetes Gateway API provider. When resolving HTTPRoute.spec.rules[].backendRefs[].filters[].extensionRef, Traefik used the backend Service namespace instead of the HTTPRoute namespace. A low-privileged route author holding a ReferenceGrant for a cross-namespace Service could therefore bind a Traefik Middleware from the backend namespace without a separate grant for that middleware, potentially injecting trusted reverse-proxy identity headers into downstream requests. The issue is fixed in version 3.7.7.