authentik: MFA Bypass via State Confusion / Parameter Injection in AuthenticatorEmailStage

authentik is an open-source identity provider. Prior to 2026.2.7, 2026.5.7, and 2026.8.2, authentik email authenticator enrollment during an authentication or enrollment flow accepts a recipient address supplied in the setup request instead of using the address already established by the flow. An actor who knows a target user's password can substitute an attacker-controlled address, receive the one-time code, and finish enrolling the factor as the target. The target must not have enrolled the email factor already. Successful enrollment gives the actor a session as the target and access to single sign-on applications behind the account. Other authenticator types are not affected. This issue is fixed in versions 2026.2.7, 2026.5.7, and 2026.8.2.