source: http://www.securityfocus.com/bid/12690/info

PBLang is reported prone to a directory traversal vulnerability. It is reported that the issue exists due to a lack of sufficient sanitization performed on user-supplied input.

A remote attacker may exploit this condition to reveal the contents of web server readable files. Reports indicate that this will allow a remote attacker to reveal account information for target users including the password hash. 

http://www.example.com/pblang/sendpm.php?to=[username]&subj=[doesntmatter]&num=1&orig=/home/public_html/pblang/db/members/[username] 