This is reported security issue in multiple browsers, which can be exploited by a malicious web site to spoof the URL displayed in the address bar, SSL certificate, and status bar.
Please see the test below for an example of how this vulnerability can be exploited.
Test Case / Demonstration
Click the link below in order to test whether or not your system is vulnerable. The test will open a new window, where the address bar writes "http://www.paypal.com/", but the page is actually displaying content from Secunia.
http://secunia.com/multiple_browsers_idn_spoofing_test/
Result
You are vulnerable, if a new window is opened displaying a Secunia page, but the address bar is displaying "http://www.paypal.com/".
