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.
Analysis and contextual insights are available on OpenCVE Cloud.
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.
Tracking
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| 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 |
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| Metrics |
cvssV3_1
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Subscriptions
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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
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OpenCVE Enrichment
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CWE-76
Improper Neutralization of Equivalent Special Elements