Directory traversal vulnerability in auth.php for PhpBB 1.4.0 through 1.4.4 allows remote attackers to read and include arbitrary files via .. (dot dot) sequences followed by NULL (%00) characters in CGI parameters, as demonstrated using the lang parameter in prefs.php.
https://exchange.xforce.ibmcloud.com/vulnerabilities/11407
http://www.securityfocus.com/bid/6889
http://archives.neohapsis.com/archives/bugtraq/2003-02/0245.html