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…

PriorityP359high8.8CVSS 3.1

AVNACLPRLUINSUCHIHAH

EPSS

0.48%

40.6th percentile

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 "";. 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.

Affected

1 ranges

Vendor	Product	Version range	Fixed in
f5	nginx_gateway_fabric	>= 2.4.0 < 2.8.0	2.8.0

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvdv4.08.7HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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