Secunia Security Advisory – Debian has issued an update for postgrey. This fixes a vulnerability, which can be exploited by malicious people to cause a DoS (Denial of Service).
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/48505/sa21164.txt
Source: https://packetstormsecurity.com/files/48505/Secunia-Security-Advisory-21164.html