CVE-2026-104939: CWE-303 in F5 NGINX Ingress Controller
Description
CVE-2026-104939 is a vulnerability in F5 NGINX Ingress Controller versions 5.6.0 up to but not including 5.7.0. It involves improper handling of HTTP responses from an OAuth Identity Provider (IdP) during external authentication, potentially allowing unauthenticated access to protected paths. This issue affects only the data plane and does not expose the control plane. The vulnerability has a high severity rating with a CVSS score of 7.5.
CVSS v3.1
Score 7.5high
Affected software
F5
NGINX Ingress Controller
pkg:github/f5/nginx-ingress-controllerRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The NGINX Ingress Controller has a vulnerability related to its externalAuth policy implementation. Specifically, it may mishandle HTTP responses from an OAuth IdP, which can result in an attacker gaining unauthenticated access to protected paths before proper external authentication occurs. This flaw is limited to the data plane and does not affect the control plane. The affected versions are from 5.6.0 up to but not including 5.7.0.
Potential Impact
Remote attackers may gain unauthenticated access to protected paths on the NGINX Ingress Controller, potentially bypassing intended authentication controls. There is no impact on the control plane, limiting the scope of the vulnerability to data plane access only.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no patch or official fix information is provided, users should monitor the vendor's advisories for updates. Until a fix is available, consider restricting access to the affected ingress controller or applying compensating controls if feasible.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- f5
- Date Reserved
- 2026-10-02T17:24:33.310Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6acf966f2cdf04f6568bce07
Added to database: 10/14/2026, 14:49:19 UTC
Last enriched: 10/14/2026, 15:03:36 UTC
Last updated: 10/14/2026, 19:00:33 UTC
Views: 12
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