dovecot - arbitrary code execution

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.

For the oldstable distribution (etch), this problem has been fixed in version
1.0.rc15-2etch5.

For the stable distribution (lenny), this problem has been fixed in version
1:1.0.15-2.3+lenny1.

For the testing distribution (squeeze) and the unstable distribution
(sid), this problem has been fixed in version 1:1.2.1-1.

We recommend that you upgrade your dovecot packages.