It was discovered that the SIEVE component of cyrus-imapd and kolab-cyrus-imapd, the Cyrus mail system, is vulnerable to a buffer overflow when processing SIEVE scripts. This can be used to elevate privileges to the cyrus 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. The update introduced by DSA 1881-1 was incomplete and the issue has been given an additional CVE id due to its complexity.