Improper access control in authentik - #VU131248
Published: May 12, 2026
Vulnerability identifier: #VU131248
CSH Severity: High
CVSS v4: 9.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass authentication and access protected backend resources.
The vulnerability exists due to improper access control in the authentik outpost nginx forward-auth integration when processing a client-controlled X-Original-URI header. A remote attacker can send a specially crafted HTTP request with an injected X-Original-URI header to bypass authentication and access protected backend resources.
Only deployments using authentik's nginx forward-auth integration are affected; Traefik, Caddy, and proxy mode deployments are not affected.
Affected software
authentik
Remediation
Install security update from vendor's website.
authentik - addressed in versions 2025.12.5, 2026.2.3