This module enables you to disable the standard Drupal login form (/user/login) so site owners can prevent interactive logins via the UI.
The module does not sufficiently block authentication when the REST/HTTP login route is used. An attacker (or legitimate user) with valid credentials can authenticate using the REST login endpoint (/user/login?_format=json) or other HTTP-based authentication routes, effectively bypassing the module’s protection of the UI login page.
This vulnerability is mitigated by the fact that an attacker must already possess valid account credentials.