Improper access control in Traefik - CVE-2026-41174
Published: May 5, 2026
Vulnerability identifier: #VU129674
CSH Severity: Low
CVSSv4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-41174
CWE-ID: CWE-284
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerable software:
Traefik
Traefik
Software vendor:
Containous
Containous
Description
The vulnerability allows a local user to bypass namespace isolation and apply middleware from another namespace.
The vulnerability exists due to improper access control in the Kubernetes CRD provider Chain middleware resolution path when processing nested middleware references in Middleware.spec.chain.middlewares[] with cross-namespace references disabled. A local user can create or update a local Chain middleware that references middleware objects in another namespace to bypass namespace isolation and apply middleware from another namespace.
Only deployments with providers.kubernetesCRD.allowCrossNamespace=false are affected.
Remediation
Install security update from vendor's website.