Traefik Kubernetes CRD allows unauthorized cross-namespace middleware binding

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Summary

CVECVE-2026-41174
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-30 21:16:33 UTC
Updated2026-04-30 21:16:33 UTC
DescriptionTraefik 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.

Risk And Classification

Primary CVSS: v4.0 4.8 MEDIUM from [email protected]

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

Problem Types: CWE-653 | CWE-863 | CWE-863 CWE-863: Incorrect Authorization | CWE-653 CWE-653: Improper Isolation or Compartmentalization

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary4.8MEDIUMCVSS: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/C...
4.0CNADECLARED4.8MEDIUMCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
None
Confidentiality
None
Integrity
None
Availability
None
Sub Conf.
Low
Sub Integrity
Low
Sub Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Traefik Traefik affected < 2.11.43 Not specified
CNA Traefik Traefik affected >= 3.7.0-ea.1, < 3.7.0-rc.2 Not specified

References

ReferenceSourceLinkTags
github.com/traefik/traefik/releases/tag/v2.11.43 [email protected] github.com
github.com/traefik/traefik/security/advisories/GHSA-xhjw-95fp-8vgq [email protected] github.com
github.com/traefik/traefik/releases/tag/v3.6.14 [email protected] github.com
github.com/traefik/traefik/commit/df00d82fc7f12e07199551832b54de6d0e55414d [email protected] github.com
github.com/traefik/traefik/releases/tag/v3.7.0-rc.2 [email protected] github.com
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