The ACL plugin in Dovecot before 1.1.4 allows attackers to bypass intended access restrictions by using the "k" right to create unauthorized "parent/child/child" mailboxes.
https://exchange.xforce.ibmcloud.com/vulnerabilities/45669
http://www.vupen.com/english/advisories/2008/2745
http://www.securityfocus.com/bid/31587
http://www.securityfocus.com/archive/1/498498/100/0/threaded
http://www.mandriva.com/security/advisories?name=MDVSA-2008:232
http://www.dovecot.org/list/dovecot-news/2008-October/000085.html
http://security.gentoo.org/glsa/glsa-200812-16.xml
http://secunia.com/advisories/33149