The UIKit component in Apple iPhone OS 3.0, and iPhone OS 3.0.1 for iPod touch, allows physically proximate attackers to discover a password by watching a user undo deletions of characters in the password.
https://exchange.xforce.ibmcloud.com/vulnerabilities/53185
http://www.securityfocus.com/bid/36335
http://support.apple.com/kb/HT3860
http://secunia.com/advisories/36677
http://lists.apple.com/archives/security-announce/2009/Sep/msg00001.html