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.
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://github.com/traefik/traefik/commit/26c96a3935cafb473f4a5bae1886560d9aa4e4f0 Patch
- https://github.com/traefik/traefik/security/advisories/GHSA-42cj-m3vj-89wv Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 5.3 · traefikNVD modified 2026-10-08 16:17
Affected (CPE criteria) 1
cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
References 3
- https://github.com/traefik/traefik/commit/26c96a3935cafb473f4a5bae1886560d9aa4e4f0 Patch
- https://github.com/traefik/traefik/security/advisories/GHSA-42cj-m3vj-89wv Vendor Advisory
- https://www.vulncheck.com/advisories/traefik-before-ingressroutetcp-serverstransport-namespace-bypass Third Party Advisory