Directory traversal vulnerability in printview.php in PNphpBB2 1.2i and earlier allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the phpEx parameter.
https://www.exploit-db.com/exploits/4796
https://exchange.xforce.ibmcloud.com/vulnerabilities/39243
http://irk4z.wordpress.com/2007/12/27/pnphpbb2-12i-printviewphp-phpex-local-file-inclusion-vuln/