Secunia Security Advisory – Debian has issued an update for courier. This fixes a vulnerability, which can be exploited by malicious people to conduct script insertion attacks.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/39784/sa16652.txt
Source: https://packetstormsecurity.com/files/39784/Secunia-Security-Advisory-16652.html