a new vulnerability has been reported in Mozilla and Mozilla Firefox, allowing malicious sites to abuse SSL certificates of other sites.

It is possible to make the browser load a valid certificate from a trusted website by using a specially crafted “onunload” event. The problem is that Mozilla loads the certificate from a trusted website and shows the “secure padlock” while actually displaying the content of the malicious website.

The URL shown in the address bar correctly reads that of the malicious website.

This has been confirmed using Mozilla Firefox 0.9.2 and Mozilla 1.7.1 on Windows and Mozilla Firefox 0.9.1 on Linux. Other versions may also be affected.

There is no patch yet.

A temporary solution would be to not follow links from untrusted websites and verify the correct URL in the address bar with the one in the SSL certificate.