Users of iPhones, iPads, and iPod touch devices running Safari on iOS 5.1 should beware of a security issue that involves address bar spoofing. The issue was discovered by David Vieira-Kurz of MajorSecurity.net, and involves "an error within the handling of URLs when using javascript's window.open() method."
What does this mean in plain English? It means that the error can be exploited to trick users into supplying personal information to a malicious website, since the Safari address bar can display