Ticket #24225: 24225.4.diff

wp-admin/includes/media.php

@@ -150 +150 @@
         // convert any remaining line breaks to <br>
         $caption = preg_replace( '/[ \n\t]*\n[ \t]*/', '<br />', $caption );
 
-        $html = preg_replace( '/(class=["\'][^\'"]*)align(none|left|right|center)\s?/', '$1', $html );
-        if ( empty($align) )
+        // Remove alignment classes
+        $html = preg_replace( '/(class=(["\'])(?:(?!\2).)*?)align(?:none|left|right|center)\s?/', '$1', $html );
+        if ( empty( $align ) )
                 $align = 'none';
 
         $shcode = '[caption id="' . $id . '" align="align' . $align     . '" width="' . $width . '"]' . $html . ' ' . $caption . '[/caption]';