authentik is an open-source Identity Provider. Prior to versions 2023.8.4 and 2023.10.2, when the default admin user has been deleted, it is potentially possible for an attacker to set the password of the default admin user without any authentication. authentik uses a blueprint to create the default admin user, which can also optionally set the default admin users' password from an environment variable. When the user is deleted, the initial-setup flow used to configure authentik after the first installation becomes available again. authentik 2023.8.4 and 2023.10.2 fix this issue. As a workaround, ensure the default admin user (Username akadmin) exists and has a password set. It is recommended to use a very strong password for this user, and store it in a secure location like a password manager. It is also possible to deactivate the user to prevent any logins as akadmin.

authentik is an open-source identity provider. When initialising a oauth2 flow with a codechallenge and codemethod (thus requesting PKCE), the single sign-on provider (authentik) must check if there is a matching and existing codeverifier during the token step. Prior to versions 2023.10.4 and 2023.8.5, authentik checks if the contents of codeverifier is matching only when it is provided. When it is left out completely, authentik simply accepts the token request with out it; even when the flow was started with a codechallenge. authentik 2023.8.5 and 2023.10.4 fix this issue.