Siri in Apple iOS before 5.1 does not properly restrict the ability of Mail.app to handle voice commands, which allows physically proximate attackers to bypass the locked state via a command that forwards an active e-mail message to an arbitrary recipient.
http://www.securitytracker.com/id?1026774
http://secunia.com/advisories/48288
http://lists.apple.com/archives/security-announce/2012/Mar/msg00001.html