Traefik is an HTTP reverse proxy and load balancer. Prior to versions 3.6.11 and 3.7.0-ea.2, Traefik's Knative provider builds router rules by interpolating user-controlled values into backtick-delimited rule expressions without escaping. In live cluster validation, Knative `rules[].hosts[]` was exploitable for host restriction bypass (for example `tenant.example.com`) || Host(`attacker.com`), producing a router that serves attacker-controlled hosts. Knative `headers[].exact` also allows rule-syntax injection and proves unsafe rule construction. In multi-tenant clusters, this can route unauthorized traffic to victim services and lead to cross-tenant traffic exposure. Versions 3.6.11 and 3.7.0-ea.2 patch the issue.
Affected: Go: github.com/traefik/traefik/v3, Go: github.com/traefik/traefik/v2
## Summary
There is a potential vulnerability in Traefik's Kubernetes Knative, Ingress, and Ingress-NGINX providers related to rule injection.
User-controlled values are interpolated into backtick-delimited Traefik router rule expressions without escaping or validation. A malicious value containing a backtick can terminate the literal and inject additional operators into Traefik's rule language, altering the parsed rule tree. In shared or multi-tenant deployments, this can bypass host and header routing constraints and redirect unauthorized traffic to victim services.
## Patches
- https://github.com/traefik/traefik/releases/tag/v3.6.11 - https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.2
## For more information
If there are any questions or comments about this advisory, please [open an issue](https://github.com/traefik/traefik/issues).
<details> <summary>Original Description</summary>
### Summary Traefik's Knative provider builds router rules by interpolating user-controlled values into backtick-delimited rule expressions without escaping. In live cluster validation, Knative `rules[].hosts[]` was exploitable for host restriction bypass (for example `tenant.example.com`) || Host(`attacker.com`), producing a router that serves attacker-controlled hosts. Knative `headers[].exact` also allows rule-syntax injection and proves unsafe rule construction. In multi-tenant clusters, this can route unauthorized traffic to victim services and lead to cross-tenant traffic…
traefik-3.6.12-1.1 on GA media
golang: archive/zip: Excessive CPU consumption when building archive index in archive/zip axios: Axios: Server-Side Request Forgery and proxy bypass due to improper hostname normalization org.eclipse.jetty/jetty-http: HTTP request smuggling via chunked extension quoted-string parsing lodash: lodash: Arbitrary code execution via untrusted input in template imports path-to-regexp: path-to-regexp: Denial of Service via crafted regular expressions Spring Boot: Spring Boot: Authentication bypass via misconfigured Health Group additional path net/url: Incorrect parsing of IPv6 host literals in net/url github.com/traefik/traefik: Traefik: Denial of Service due to incomplete TLS handshake crypto/x509: Incorrect enforcement of email constraints in crypto/x509 rollup: Rollup: Remote Code Execution via Path Traversal Vulnerability github.com/traefik/traefik: Traefik: Information disclosure due to case-insensitive Connection header processing Traefik: github.com/traefik/traefik: Traefik: mTLS bypass allows unauthorized service access via fragmented ClientHello. github.com/traefik/traefik: Traefik: Cross-tenant traffic exposure and host restriction bypass via rule-syntax injection in Knative provider google.golang.org/grpc/grpc-go: google.golang.org/grpc/authz: gRPC-Go: Authorization bypass due to improper HTTP/2 path validation github.com/traefik/traefik: Traefik: Authentication bypass via non-canonical HTTP header injection @fastify/reply-from: @fastify/http-proxy: Fastify Reply From a…