Description
An authentication and authorization bypass vulnerability exists in F5 NGINX Kubernetes Ingress Controller (NIC) when configured with the `ExternalAuth` policy or Ingress external authentication. Client-supplied X-Forwarded-Prefix, X-Forwarded-URI, X-Original-URI, and X-Forwarded-Method routing and method headers are forwarded unsanitized into the internal authentication subrequest (handled by the NGINX auth_request directive). As a result, an unauthenticated, remote attacker may spoof request attributes evaluated by the external authentication provider.
Impact:
This vulnerability may allow remote attackers
unauthenticated
access to protected
paths. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| F5 | NGINX Ingress Controller | 5.5.0 – < 5.7.0 | 5.7.0 |
Advisories 1
- WID-SEC-2026-3948 NGINX: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
References
- https://my.f5.com/manage/s/article/K000162611 vendor-advisory