The ACL plugin in Dovecot 1.2.x before 1.2.13 propagates INBOX ACLs to newly created mailboxes in certain configurations, which might allow remote attackers to read mailboxes that have unintended weak ACLs.
http://www.vupen.com/english/advisories/2011/0301
http://www.vupen.com/english/advisories/2010/2840
http://www.ubuntu.com/usn/USN-1059-1
http://www.securityfocus.com/bid/41964
http://www.openwall.com/lists/oss-security/2010/09/16/17
http://www.openwall.com/lists/oss-security/2010/09/16/14
http://www.mandriva.com/security/advisories?name=MDVSA-2010:217
http://www.dovecot.org/list/dovecot-news/2010-July/000163.html
http://secunia.com/advisories/43220
http://lists.opensuse.org/opensuse-security-announce/2010-09/msg00006.html