Flat PHP Board 1.2 and earlier stores sensitive information under the web root with insufficient access control, which allows remote attackers to obtain credentials via a direct request for the username php file for any user account in users/.
https://www.exploit-db.com/exploits/4705
http://www.securityfocus.com/bid/26782
http://www.securityfocus.com/archive/1/484803/100/100/threaded