Secunia Security Advisory – Debian has issued an update for asterisk. This fixes multiple vulnerabilities, which can be exploited by malicious people to determine valid user names and to cause a DoS (Denial of Service).
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/83935/sa37677.txt
Source: https://packetstormsecurity.com/files/83935/Secunia-Security-Advisory-37677.html