Traefik namespace confusion in Kubernetes Gateway API HTTPRoute

Severity: medium · CVSS 5.3 · Published 2026-07-22

Traefik, a popular open-source edge router and load balancer, contains a security flaw in how it handles Kubernetes Gateway API configurations. An attacker with limited permissions could bypass security boundaries to reuse sensitive configuration settings (Middlewares) from other parts of the system. This could allow an attacker to impersonate other users or gain unauthorized access to internal applications by injecting fake identity information into web requests.

Technologies: github.com/traefik/traefik (Go). Vendors: Go.

Quick answers

Is This vulnerability exploited in the wild?
No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
How severe is This vulnerability?
Medium severity, with a CVSS score of 5.3, published 22 July 2026.
Which products and versions are affected?
github.com/traefik/traefik (Go) >= 3.7.0, < 3.7.7.
Is there a fix for This vulnerability?
A patch was published on 2026-08-05: Advisory updated to reflect patch availability in 3.7.7 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is This vulnerability attacked?
It is attacked over the network, in a software library.
Am I affected?
Check whether you run github.com/traefik/traefik (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A namespace confusion vulnerability exists in Traefik's Kubernetes Gateway API provider when resolving HTTPRoute extension references. The software incorrectly uses the backend Service namespace instead of the HTTPRoute namespace when processing 'HTTPRoute.spec.rules[].backendRefs[].filters[].extensionRef'. A low-privileged attacker with a ReferenceGrant for a cross-namespace Service can exploit this to bind a Traefik Middleware from that backend namespace without explicit authorization. This can be used to attach sensitive Middlewares, such as those that inject trusted reverse-proxy identity headers (e.g., X-WEBAUTH-USER), potentially leading to authentication bypass in downstream applications. The issue is fixed in version 3.7.7.

Affected products

  • Traefik Labs Traefik >= 3.7.0, < 3.7.7

Timeline

  • 2026-07-09: disclosed: Original advisory published by Traefik maintainers
  • 2026-07-22: advisory: NVD and GitHub Advisory Database entries published
  • 2026-08-05: patched: Advisory updated to reflect patch availability in 3.7.7

References

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