phpBB 1.4.4 and earlier with BBcode allows remote attackers to cause a denial of service (CPU consumption) and corrupt the database via null \0 characters within [code] tags.
http://www.securityfocus.com/bid/4434
http://www.securityfocus.com/bid/4432
http://www.iss.net/security_center/static/8764.php
http://online.securityfocus.com/archive/1/265798
http://marc.info/?l=bugtraq&m=101794993119738&w=2
http://archives.neohapsis.com/archives/vulnwatch/2002-q2/0005.html