Actually, that PHP flaw was pretty serious, however, the one that is worse is with PHPBB that allows Santy.
There was a bug in the highlighting code -- Some of phpbb's mirrors on sourceforge have the fix, some don't.
In viewtopic.php, you need to look for
http://www.phpbb.com/phpBB/viewtopic.php?f=14&t=240513
In my mind, this one is much more serious.