Ticket #39645: 39645.3.diff

wp-includes/user.php

@@ -3089 +3089 @@
         // Check the username.
         if ( '' === $sanitized_user_login ) {
                 $errors->add( 'empty_username', __( '<strong>Error</strong>: Please enter a username.' ) );
+        } 
+        // Prevent the use of 'admin' username to help combat brute force attempts. 
+          elseif ( strtolower( $sanitized_user_login ) == 'admin' ) {   
+                $errors->add( 'invalid_username', __( '<strong>Error</strong>: This username is invalid for security reasons. Please enter a valid username.' ) );
         } elseif ( ! validate_username( $user_login ) ) {
                 $errors->add( 'invalid_username', __( '<strong>Error</strong>: This username is invalid because it uses illegal characters. Please enter a valid username.' ) );
                 $sanitized_user_login = '';