The WPS Hide Login WordPress plugin before 1.9.16.4 does not prevent redirects to the login page via the auth_redirect WordPress function, allowing an unauthenticated visitor to access the hidden login page.
The WPS Hide Login plugin for WordPress is vulnerable to Login Page Disclosure in all versions up to, and including, 1.9.15.2. This is due to a bypass that is created when the 'action=postpass' parameter is supplied. This makes it possible for attackers to easily discover any login page that may have been hidden by the plugin.