Junglewise Threat Intelligence

Traefik path traversal in Kubernetes Ingress NGINX RewriteTarget

Severity: high · CVSS 7.8 · Published 2026-08-01

Executive brief

Traefik, a popular cloud-native application proxy, contains a vulnerability in how it handles specific URL rewriting rules for Kubernetes environments. An attacker can craft a malicious web request that tricks the system into bypassing security controls like login screens or access restrictions. This could allow unauthorized access to sensitive administrative data or internal services that were intended to be protected.

Technical details

A path traversal vulnerability exists in Traefik's Kubernetes Ingress NGINX provider's RewriteTarget middleware. When an Ingress path uses a regex that captures attacker-controlled text without requiring a path separator (e.g., /api(.*) with rewrite target /$1), a crafted request like /api../admin is rewritten to /../admin. Because Traefik forwards this rewritten path without post-replacement normalization validation, a backend that normalizes dot segments will resolve the path to a protected endpoint (e.g., /admin). This allows an attacker to bypass middlewares such as BasicAuth, DigestAuth, or ForwardAuth that are attached to the intended protected router. The issue is fixed in v3.7.8.

Affected products

  • Traefik Labs Traefik >= v3.7.0, <= v3.7.7

Timeline

  • 2026-07-16: advisory: Original advisory GHSA-8rxv-jg7p-wvg3 published
  • 2026-08-01: disclosed: Duplicate advisory GHSA-7qf5-7ppr-87v8 published
  • 2026-08-06: patched: Duplicate advisory withdrawn in favor of original GHSA-8rxv-jg7p-wvg3

References

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