Cyber Resilience

CVE-2026-41174

Access Control in Traefik ≤ 2.11.43

Public PoCAccess Control
Published
30 April 2026
Modified
01 May 2026
Patch / advisory
CVSS Score v4 4.8
Click a component to see what it means
Raw vectorCVSS: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
EPSS Score 0.0025 17th percentile
Risk Priority 35 floored blend · peak EPSS

Summary

CVE-2026-41174 is a medium-severity Improper Isolation or Compartmentalization (CWE-653) vulnerability in Traefik Traefik. Its CVSS base score is 4.8 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 17th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
Why these techniques?

Bypass of documented cross-namespace isolation in the Kubernetes CRD provider directly enables privilege escalation by allowing unauthorized middleware references from other namespaces.

Confidence: MEDIUM · MITRE ATT&CK Enterprise v19.0

CVEs Like This One

CVE-2026-54765Same product: Traefik Traefik
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CVE-2026-33433Same product: Traefik Traefik
CVE-2026-29777Same product: Traefik Traefik
CVE-2026-41263Same product: Traefik Traefik
CVE-2026-35051Same product: Traefik Traefik
CVE-2026-53622Same product: Traefik Traefik
CVE-2026-44774Same product: Traefik Traefik
CVE-2026-32595Same product: Traefik Traefik
CVE-2026-26998Same product: Traefik Traefik

Affected Assets

traefik
traefik
3.7.0 · ≤ 2.11.43 · 3.0.0 — 3.6.14

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)
  • AC-3 Access Enforcement
  • AC-4 Information Flow Enforcement
  • SC-7 Boundary Protection
Detect
Catch it (NIST detect / respond)

Harden
Shrink the surface (DISA STIG)
  • 13 hardening rules · 10 OS baselines
Validate
Prove the fix (OWASP ASVS)

Mitigating Controls (NIST 800-53 r5) AI

prevent

Directly enforces the documented cross-namespace isolation policy (allowCrossNamespace=false) that the CVE bypasses for Chain middleware references.

prevent

Enforces information-flow boundaries between Kubernetes namespaces for middleware objects, which the flawed CRD provider logic fails to uphold.

prevent

Provides boundary protection that can be used to isolate namespaces and block unauthorized cross-namespace middleware resolution at the ingress layer.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-05 full match
prevents

Least-privilege policy directly enforces separation of privilege levels and access rights.

PR.IR-01 mostly match
prevents

Network and environment segmentation implements the isolation required to prevent unauthorized cross-compartment access.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

degrades

Segregation of duties directly enforces separation of privilege levels and functions.

prevents

Network segregation is a classic technical control for isolating different privilege domains.

prevents

Secure system architecture principles explicitly call for isolation and least-privilege boundaries.

prevents

Separation of development, test and production environments is a direct application of compartmentalization.

degrades

Access control policies establish the boundaries that isolation must enforce.

degrades

Managing access rights is the operational mechanism for compartmentalizing privileges.

References