Cross-site request forgery (CSRF) vulnerability in privmsg.php in phpBB 2.0.22 allows remote attackers to delete private messages (PM) as arbitrary users via a deleteall action.
http://www.securityfocus.com/archive/1/487004/100/0/threaded
http://www.debian.org/security/2008/dsa-1488
http://securityreason.com/securityalert/3585
http://secunia.com/advisories/28871