Ticket #34090: 34090.diff

src/wp-includes/shortcodes.php

@@ -88 +88 @@
  */
 function add_shortcode($tag, $func) {
         global $shortcode_tags;
+        
+        if ( '' == $tag || 0 !== preg_match( '@[<>&/\[\]\x00-\x20]@', $tag ) ) {
+                _doing_it_wrong( __FUNCTION__, __( 'Invalid shortcode name. Do not use reserved chars: & / < > [ ]' ), '4.4' );
+                return;
+        }
+        
         $shortcode_tags[ $tag ] = $func;
 }