Debian Security Advisory 1629-1 – Sebastian Krahmer discovered that Postfix, a mail transfer agent, incorrectly checks the ownership of a mailbox. In some configurations, this allows for appending data to arbitrary files as root.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/69197/dsa-1629-1.txt
Source: https://packetstormsecurity.com/files/69197/Debian-Linux-Security-Advisory-1629-1.html