CVE 2008-4907
The message parsing feature in Dovecot 1.1.4 and 1.1.5, when using the FETCH ENVELOPE command in the IMAP client, allows remote attackers to cause a denial of service (persistent crash) via an email with a malformed From address, which triggers an assertion error, aka "invalid message address parsing bug."
See the 
CVE page on Mitre.org
for more details.
