A security issue was discovered in ingress-nginx where the protection afforded by the `auth-url` Ingress annotation may not be effective in the presence of a specific misconfiguration. If the ingress-nginx controller is configured with a default custom-errors configuration that includes HTTP errors 401 or 403, and if the configured default custom-errors backend is defective and fails to respect the X-Code HTTP header, then an Ingress with the `auth-url` annotation may be accessed even when authentication fails. Note that the built-in custom-errors backend works correctly. To trigger this issue requires an administrator to specifically configure ingress-nginx with a broken external component.
Published: 2026-02-03
Updated: 2026-04-15
Named Vulnerability: GO-2026-4419Named Vulnerability: GHSA-4g2f-xcph-2335
Base Score: 2.1
Vector: CVSS2#AV:N/AC:H/Au:S/C:P/I:N/A:N
Severity: Low
Base Score: 3.1
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Severity: Low
EPSS: 0.00341