Vulnerability CVE-2026-41174: Information

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.

Severity: MEDIUM (4.8)
Vector: 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
Severity: MEDIUM (6.4)
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Published: April 30, 2026
Modified: May 1, 2026
Error type identifier: CWE-653CWE-863

Fixed packages

Package name
Branch
Fixed in version
Version from repository
Errata ID
Task #
State
traefiksisyphus3.6.15-alt13.6.15-alt1ALT-PU-2026-7142-5417190Fixed
traefiksisyphus_riscv643.6.15-alt13.6.15-alt1ALT-PU-2026-7534-1-Fixed
traefiksisyphus_loongarch643.6.15-alt13.6.15-alt1ALT-PU-2026-7499-1-Fixed
traefikp113.6.15-alt13.6.15-alt1ALT-PU-2026-7164-5417230Fixed
traefikc10f23.6.15-alt13.6.15-alt1ALT-PU-2026-7154-5417229Fixed

References to Advisories, Solutions, and Tools

    1. cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
      End excluding
      2.11.43

      cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
      Start including
      3.0.0
      End excluding
      3.6.14

      cpe:2.3:a:traefik:traefik:3.7.0:ea1:*:*:*:*:*:*

      cpe:2.3:a:traefik:traefik:3.7.0:ea2:*:*:*:*:*:*

      cpe:2.3:a:traefik:traefik:3.7.0:ea3:*:*:*:*:*:*

      cpe:2.3:a:traefik:traefik:3.7.0:rc1:*:*:*:*:*:*