imapsync before 1.584, when running with the --tls option, attempts a cleartext login when a certificate verification failure occurs, which allows remote attackers to obtain credentials by sniffing the network.
https://lists.fedoraproject.org/pipermail/package-announce/2014-February/128293.html
https://github.com/imapsync/imapsync/issues/15
https://bugs.mageia.org/show_bug.cgi?id=12770
http://www.mandriva.com/security/advisories?name=MDVSA-2014:060
http://www.linux-france.org/prj/imapsync_list/msg01910.html
http://www.linux-france.org/prj/imapsync_list/msg01907.html