pSlash PHP script 0.7 and earlier allows remote attackers to execute arbitrary code by including files from remote web sites, using an HTTP request that modifies the includedir variable.
http://www.securityfocus.com/bid/3395
http://www.iss.net/security_center/static/7215.php
http://archives.neohapsis.com/archives/bugtraq/2001-10/0012.html