Ticket #8763: patch.diff

media.php

@@ -684 +684 @@
                 if ( $captiontag && trim($attachment->post_excerpt) ) {
                         $output .= "
                                 <{$captiontag} class='gallery-caption'>
-                                {$attachment->post_excerpt}
+                                {" . wp_specialchars($attachment->post_excerpt) . "}
                                 </{$captiontag}>";
                 }
                 $output .= "</{$itemtag}>";