Executive brief
authentik is an open-source identity provider used to manage user logins and access to various applications. A security flaw in its WS-Federation component allows attackers to redirect a user's login credentials to a malicious server. If successful, an attacker could impersonate the victim and gain unauthorized access to the applications the victim is permitted to use.
Technical details
The WS-Federation provider in authentik used a raw string prefix check to validate the 'wreply' parameter instead of proper URL parsing. An attacker can bypass this check by providing a URL that starts with the legitimate domain but belongs to a different origin (e.g., https://portal.example.com.evil.tld/). When a victim uses a crafted login link, their browser will POST the signed WS-Federation response (wresult) to the attacker's infrastructure. This signed artifact can often be replayed to the legitimate application to impersonate the victim. The vulnerability is patched in versions 2026.2.3 and 2025.12.5.
Affected products
- goauthentik authentik < 2026.2.3, < 2025.12.5
Timeline
- 2026-05-12: advisory: GitHub advisory published by maintainers
- 2026-06-02: disclosed: CVE published to NVD