CVE-2026-41174: Traefik Kubernetes CRD allows unauthorized cross-namespace middleware binding

CVE-2026-41174 PUBLISHED CVSS 6.400000095367432 MEDIUM

Traefik Kubernetes CRD allows unauthorized cross-namespace middleware binding

Record from NVD · Published April 24, 2026

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.

EPSS 0.25% · 17.0th percentile

Fixed versions

Upgrade to a fixed version or later. Language registries are listed first, then Linux distributions, then vendor products.

Package	Ecosystem	Fixed in
traefik	DHI	3.7.0-rc.2, 3.6.14, 2.11.43

Risk scores

CVSS 3.1

6.400000095367432

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

EPSS Score

0.25%

17.0th percentile

Affected products

Vendor	Product	Versions
traefik	traefik	0, 3.0.0, 3.7.0

Timeline

Apr 24, 2026 CVE Published
Apr 24, 2026 CVE Updated
Apr 24, 2026 PoC Published (2 in total, the first dated here)
May 1, 2026 Security Advisory
May 18, 2026 EPSS Score (30 in total, the first dated here)
Jul 27, 2026 Coalition ESS Score

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