NGINX Gateway Fabric has a vulnerability when it renders the spec.basic.realm (and spec.jwt.realm) field of a namespaced AuthenticationFilter verbatim, unescaped and unvalidated, into the shared data-plane nginx.conf as auth_basic "<realm>";. A namespaced authenticated attacker that configures AuthenticationFilter CRD to an HTTPRoute/GRPCRoute on a shared Gateway can craft a realm value that closes the quoted directive and the enclosing location {} block and injects arbitrary NGINX directives into that Gateway's data-plane config.
Impact
A remote authenticated attacker can send crafted requests to configure NGINX Gateway Fabric AuthenticationFilter CRD and may be able to read every co-located tenant's mounted secrets, SSRF via proxy_pass, reading the pod ServiceAccount token, or hijacking other tenants' routes. There is no data plane exposure; this is a control plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Metrics
Affected Vendors & Products
No advisories yet.
Solution
No solution given by the vendor.
Workaround
As this attack is conducted by authenticated users with Kubernetes Role-based Access Control (RBAC) write access to AuthenticationFilter CRD and Secrets, the only complete mitigation is to restrict that access to fully trusted administrators only.
| Link | Providers |
|---|---|
| https://my.f5.com/manage/s/article/K000162609 |
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Wed, 14 Oct 2026 15:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Description NGINX Gateway Fabric has a vulnerability when it renders the spec.basic.realm (and spec.jwt.realm) field of a namespaced AuthenticationFilter verbatim, unescaped and unvalidated, into the shared data-plane nginx.conf as auth_basic "<realm>";. A namespaced authenticated attacker that configures AuthenticationFilter CRD to an HTTPRoute/GRPCRoute on a shared Gateway can craft a realm value that closes the quoted directive and the enclosing location {} block and injects arbitrary NGINX directives into that Gateway's data-plane config. Impact A remote authenticated attacker can send crafted requests to configure NGINX Gateway Fabric AuthenticationFilter CRD and may be able to read every co-located tenant's mounted secrets, SSRF via proxy_pass, reading the pod ServiceAccount token, or hijacking other tenants' routes. There is no data plane exposure; this is a control plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. | |
| Title | NGINX Gateway Fabric vulnerability | |
| Weaknesses | CWE-76 | |
| References |
| |
| Metrics |
cvssV3_1
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Projects
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Status: PUBLISHED
Assigner: f5
Published:
Updated: 2026-10-14T14:40:27.849Z
Reserved: 2026-09-30T21:56:14.612Z
Link: CVE-2026-91184
No data.
Status : Awaiting Analysis
Published: 2026-10-14T15:17:26.420
Modified: 2026-10-14T16:04:11.750
Link: CVE-2026-91184
No data.
OpenCVE Enrichment
No data.