high CVSS 7.5 EPSS 0.66%

CVE-2026-67309·Traefik vulnerability

Traefik versions >= v3.7.0 and <= v3.7.7 contain a path traversal vulnerability in the Kubernetes Ingress NGINX provider's RewriteTarget middleware (generated from the nginx.ingress.kubernetes.io/rewrite-target annotation). When an Ingress path uses a regex that captures attacker-controlled text without requiring a path separator (e.g., path /api(.*) with rewrite target /$1), a crafted request such as /api../admin matches the public router, is rewritten to a dot-segment traversal path (/../admin), and is forwarded without post-replacement normalization validation. A backend that normalizes dot segments resolves the path to a protected endpoint (e.g., /admin) reachable only through a separate router secured with BasicAuth, DigestAuth, or ForwardAuth, resulting in route-level authentication bypass. The issue is fixed in v3.7.8.

Severity
high
Software
Traefik
Fixed in
3.7.8
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at 0.66% — higher than 51% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2026-67309 scores 7.5 on CVSS, so a successful attack would be serious — but at 0.66%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

From: 3.7.0

Until: 3.7.8

Fixed in: 3.7.8

How to fix this CVE

Upgrade Traefik to version 3.7.8 or later to patch a critical path traversal vulnerability in the Kubernetes Ingress NGINX RewriteTarget middleware. This vulnerability allows attackers to bypass authentication controls by crafting requests with dot-segment sequences that traverse to protected routes. Immediately apply this update if you are running Traefik v3.7.0 through v3.7.7 with Kubernetes Ingress annotations configured.

sudo dnf update traefik (ensure version 3.7.8 or later is available from your repository)

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST|GET /api\.\./(admin|protected|internal).*

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement WAF rules to reject requests containing consecutive dot-segment sequences (/../ or ..\ patterns) in the URL path before they reach the Traefik router. Additionally, normalize and validate all rewritten paths server-side to prevent traversal attacks.

How to check if you are affected

  1. Check installed Traefik version: traefik version | grep Version
  2. Review Kubernetes Ingress resources for nginx.ingress.kubernetes.io/rewrite-target annotations: kubectl get ingress -A -o json | jq '.items[] | select(.metadata.annotations["nginx.ingress.kubernetes.io/rewrite-target"] != null)'
  3. Examine access logs for requests containing dot-segment sequences (../) targeting paths that should be protected: grep -E '\.\./' /var/log/traefik/access.log
  4. Verify Traefik has been restarted with the patched version: traefik version and confirm it shows v3.7.8 or higher

FAQ

What is CVE-2026-67309?

CVE-2026-67309 is a path traversal vulnerability in Traefik's Kubernetes Ingress NGINX provider that allows attackers to bypass route-level authentication by injecting dot-segment sequences into requests that get rewritten through the RewriteTarget middleware. This results in unauthorized access to protected endpoints that should require BasicAuth, DigestAuth, or ForwardAuth credentials.

Is CVE-2026-67309 being actively exploited?

No, CVE-2026-67309 is not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog, and no public exploits have been reported. However, the attack pattern is straightforward, so prompt patching is recommended.

What versions of Traefik are affected by CVE-2026-67309?

Traefik versions 3.7.0 through 3.7.7 are vulnerable. Version 3.7.8 and later contain the fix.

How do I check if my server is vulnerable to CVE-2026-67309?

Run 'traefik version' and check if the reported version is between 3.7.0 and 3.7.7. Then verify if you have any Kubernetes Ingress resources with the 'nginx.ingress.kubernetes.io/rewrite-target' annotation by running 'kubectl get ingress -A -o json | jq '.items[] | select(.metadata.annotations["nginx.ingress.kubernetes.io/rewrite-target"] != null)''.

Does Defensia detect CVE-2026-67309?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Traefik is installed on a monitored server, CVE-2026-67309 will appear in your dashboard with remediation steps.

Related Traefik CVEs

CVE-2026-53622CVSS 10Traefik is an HTTP reverse proxy and load balancer. Versions prior to 3.7.3, 3.6.18, and 2.11.51 have a critical vulnerability in Traefik's HTTP/3 (QUIC) TLS configuration selection that allows unauthenticated clients to bypass router-specific mTLS enforcement. When HTTP/3 is enabled on an entrypoint, the TLS handshake selects the applicable TLS configuration through an exact, case-sensitive lookup on the SNI value, which fails to match wildcard host patterns (e.g., *.example.com) or case variants of the configured hostname. Because the handshake falls back to the default TLS configuration — which may not require client certificates — a client can complete the QUIC handshake without presenting a certificate, while the subsequent HTTP routing layer still dispatches the request to a backend protected by a router-specific mTLS policy. The issue affects deployments where HTTP/3 is enabled, a router uses a wildcard Host rule or case-insensitive hostname matching, a router-specific TLSOptions enforces client certificate authentication, and UDP access to the entrypoint is reachable by an attacker. This vulnerability is fixed in versions 3.7.3, 3.6.18, and 2.11.51.
CVE-2026-48491CVSS 10Traefik is an HTTP reverse proxy and load balancer. From 3.7.0 until 3.7.3, there is a high severity vulnerability in Traefik's domain-fronting protection (SNICheck) that allows an unauthenticated client to bypass mutual TLS enforced through wildcard router TLSOptions. When a router uses a wildcard host rule such as Host(*.example.com) with stricter TLS options (for example RequireAndVerifyClientCert), SNICheck resolves the TLS options for the HTTP Host header using exact map lookups only and never applies wildcard matching. If another permissive SNI is served on the same entrypoint, an attacker can complete the TLS handshake under the permissive options and then send an HTTP Host header targeting the wildcard-protected backend, reaching it without presenting a client certificate. This affects the regular HTTPS / HTTP-2 path and does not require HTTP/3. This vulnerability is fixed in 3.7.3.
CVE-2026-48020CVSS 10Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.48, 3.6.19, and 3.7.3, there is a high severity vulnerability in Traefik's StripPrefix middleware that allows an unauthenticated attacker to bypass route-level authentication and authorization. When a public router matches on a PathPrefix rule and applies the StripPrefix middleware, a request path containing .. or its percent-encoded form %2e%2e can match the public route at routing time and then, after the prefix is stripped and the path is normalized, resolve to a path served by a separate, authenticated router. As a result, an attacker can reach protected backend paths — such as admin or internal configuration endpoints — without satisfying the authentication middleware attached to the protected router. This vulnerability is fixed in 2.11.48, 3.6.19, and 3.7.3.
CVE-2026-54763CVSS 10Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's BasicAuth, DigestAuth, and ForwardAuth middlewares strip canonical-cased spoofed identity headers before writing Traefik's own value, but do not account for underscore-variant header names, which many backends normalize identically to dashed forms. An attacker able to reach a protected route can inject an underscore-variant header that survives Traefik's stripping and reaches the backend alongside, or on the unauthenticated ForwardAuth authResponseHeaders path instead of, the value Traefik intended to set, spoofing identity or authorization context. This issue is fixed in versions v2.11.51, v3.6.22, and v3.7.6.
CVE-2026-44774CVSS 9.9Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.46, 3.6.17, and 3.7.1, Traefik's Kubernetes Gateway API provider allows a tenant with HTTPRoute creation permissions to expose the REST provider handler, bypassing the providers.rest.insecure=false setting. The Gateway provider accepts any TraefikService backend reference whose name ends with @internal, making it possible to route traffic to rest@internal in addition to the intended api@internal. In shared Gateway deployments where the REST provider is enabled, this allows a low-privileged actor to gain live dynamic configuration write access to Traefik, enabling unauthorized reconfiguration of routers and services. This vulnerability is fixed in 2.11.46, 3.6.17, and 3.7.1.

References

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