Directory traversal vulnerability in include/common.php in PunBB before 1.2.14 allows remote authenticated users to include and execute arbitrary local files via a .. (dot dot) in the language parameter, related to register.php storing a language value in the users table.
http://www.wargan.org/index.php/2006/10/29/4-punbb-1213-multiple-vulnerabilities
http://www.vupen.com/english/advisories/2006/4256
http://www.securityfocus.com/archive/1/450055/100/0/threaded
http://www.punbb.org/changelogs/1.2.13_to_1.2.14.txt
http://securitytracker.com/id?1017131