Debian Security Advisory 1892-1 – It was discovered that the SIEVE component of dovecot, a mail server that supports mbox and maildir mailboxes, is vulnerable to a buffer overflow when processing SIEVE scripts. This can be used to elevate privileges to the dovecot system user. An attacker who is able to install SIEVE scripts executed by the server is therefore able to read and modify arbitrary email messages on the system.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/81582/dsa-1892-1.txt
Source: https://packetstormsecurity.com/files/81582/Debian-Linux-Security-Advisory-1892-1.html