CVE-2026-91184
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.
Executive briefing
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Evidence confidence: Not assessed Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:Not supplied
No CVSS vector is currently available in the source record.
Technical explanation & impact
Technical root-cause details are not available in the current source record.
Assess the impact using the published CVSS metrics and the affected vendor component.
Affected products and versions
NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.
Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.
Vendor advisories, patches & exploit references
No external references are currently supplied in the CVE record.