Ticket #21512: 21512.patch

wp-includes/comment.php

@@ -655 +655 @@
                 $post_author = $wpdb->get_var($wpdb->prepare("SELECT post_author FROM $wpdb->posts WHERE ID = %d LIMIT 1", $comment_post_ID));
         }
 
-        if ( $user && ( $user_id == $post_author || $user->has_cap('moderate_comments') ) ) {
+        if ( isset( $user ) && ( $user_id == $post_author || $user->has_cap( 'moderate_comments' ) ) ) {
                 // The author and the admins get respect.
                 $approved = 1;
          } else {