Index: filter.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/filter/filter.module,v
retrieving revision 1.239
diff -u -r1.239 filter.module
--- filter.module	30 Dec 2008 16:43:17 -0000	1.239
+++ filter.module	20 Jan 2009 16:19:02 -0000
@@ -825,6 +825,7 @@
   $match[2] = decode_entities($match[2]);
   $caption = check_plain(_filter_url_trim($match[2]));
   $match[2] = check_url($match[2]);
+  $match[2] = strip_tags($match[2]);
   return $match[1] . '<a href="' . $match[2] . '" title="' . $match[2] . '">' . $caption . '</a>' . $match[5];
 }