Messages in Apple iOS before 9.3 does not ensure that an auto-fill action applies to the intended message thread, which allows remote authenticated users to obtain sensitive information by providing a crafted sms: URL and reading a thread.
https://support.apple.com/HT206166
http://www.securitytracker.com/id/1035353
http://lists.apple.com/archives/security-announce/2016/Mar/msg00000.html