Description
Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a potential vulnerability in Traefik's Kubernetes CRD provider cross-namespace isolation enforcement. When providers.kubernetesCRD.allowCrossNamespace=false, Traefik correctly rejects direct cross-namespace middleware references from IngressRoute objects, but fails to apply the same restriction to middleware references nested inside a Chain middleware's spec.chain.middlewares[]. An actor with permission to create or update Traefik CRDs in their own namespace can exploit this to cause Traefik to resolve and apply middleware objects from another namespace, bypassing the documented isolation boundary. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.
Affected products
traefik: traefik
References5
- github.com/traefik/traefik/security/advisories/GHSA-xhjw-95fp-8… ExploitPatchVendor Advisory
- github.com/traefik/traefik/commit/df00d82fc7f12e07199551832b54d… Patch
- github.com/traefik/traefik/releases/tag/v2.11.43 ProductRelease Notes
- github.com/traefik/traefik/releases/tag/v3.6.14 ProductRelease Notes
- github.com/traefik/traefik/releases/tag/v3.7.0-rc.2 ProductRelease Notes
Metrics
- CVSS 3.1
-
6.4
MEDIUM
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N - CVSS 4.0
-
4.8
MEDIUM
Score source: CNA
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 17 · as of 13 November 2026
- CWE
- CWE-653CWE-863
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