Ticket #27317: 27317.2.patch

wp-admin/includes/user.php

@@ -176 +176 @@
                 $user_id = wp_update_user( $user );
         } else {
                 $user_id = wp_insert_user( $user );
-                wp_new_user_notification( $user_id, isset( $_POST['send_password'] ) ? wp_unslash( $pass1 ) : '' );
+                if (!is_wp_error($user_id))
+                        wp_new_user_notification( $user_id, isset( $_POST['send_password'] ) ? wp_unslash( $pass1 ) : '' );
         }
         return $user_id;
 }

wp-includes/user.php

@@ -1542 +1542 @@
         if ( !$update && username_exists( $user_login ) )
                 return new WP_Error( 'existing_user_login', __( 'Sorry, that username already exists!' ) );
 
+        if ( in_array( $user_login, apply_filters( 'illegal_user_logins', array() ) ) ) {
+            return new WP_Error( 'illegal-user-login', __( "User login value is not permitted." ) );
+
         if ( empty($user_nicename) )
                 $user_nicename = sanitize_title( $user_login );