Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 state value to replay the callback and sign that victim into an attacker-controlled account.

AshAuthentication.Strategy.OAuth2.Plug.callback/2 clears the stored sessionparams through a rebinding step inside its with chain, conn <- deletesession(conn, sessionkey). Elixir evaluates the else block in the scope enclosing the with, so every failure path (the provider returning ?error=accessdenied, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches storeauthenticationresult/2 holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.

This issue affects ashauthentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.