Vulnerability · Published Apr 30, 2026 · Assigned by GitHub_M

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

Medium 4.8

In plain English

A medium-severity incorrect authorization in traefik from traefik. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 17% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)4.8Medium

Exploit odds (30 days)0.3%top 83.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/traefik/traefik	no fix listed	GHSA-xhjw-95fp-8vgq
Go	github.com/traefik/traefik	no fix listed	GO-2026-5760
Go	github.com/traefik/traefik/v2	2.11.43	GHSA-xhjw-95fp-8vgq
Go	github.com/traefik/traefik/v2	2.11.43	GO-2026-5760
Go	github.com/traefik/traefik/v3	3.7.0-rc.2	GHSA-xhjw-95fp-8vgq
Go	github.com/traefik/traefik/v3	3.6.14, 3.7.0-rc.2	GO-2026-5760
Go	github.com/traefik/traefik/v3	3.6.14	GHSA-xhjw-95fp-8vgq

Affected products (as reported)

Vendor	Product	Versions
traefik	traefik	< 2.11.43>= 3.7.0-ea.1, < 3.7.0-rc.2

Weakness: CWE-863, CWE-653 · 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

References

https://github.com/traefik/traefik/security/advisories/GHSA-xhjw-95fp-8vgq x_refsource_CONFIRM
https://github.com/traefik/traefik/commit/df00d82fc7f12e07199551832b54de6d0e55414d x_refsource_MISC
https://github.com/traefik/traefik/releases/tag/v2.11.43 x_refsource_MISC
https://github.com/traefik/traefik/releases/tag/v3.6.14 x_refsource_MISC
https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2 x_refsource_MISC