Open Directory Client in Apple OS X before 10.10.3 sends unencrypted password-change requests in certain circumstances involving missing certificates, which allows remote attackers to obtain sensitive information by sniffing the network.
https://support.apple.com/HT204659
http://www.securitytracker.com/id/1032048
http://lists.apple.com/archives/security-announce/2015/Apr/msg00001.html