Originally posted by Ragnorak
What about having tabs open in another firefox browser window? I also do my banking as 1 tab in a window of at least 10 tabs. I didn't realise it was dodgy.
Very serious. They aren't easy targets for a security hole, but they are there. When there's money at stake, somebody is sure to put the work in.
Bit of a summary if you can't be bothered with the link:
Features built into browsers makes it possible for malicious websites to change the content of pop-up windows created by trusted websites (such as online banks). Users would have no inkling that potentially hostile content has been injected into a pop-up window. Exploits rely on misusing browser functionality rather than taking advantage of a software bug. Secunia has confirmed the vulnerability on fully patched versions of Internet Explorer 6.0 and Windows XP SP1 and SP2 (advisory here), Mozilla 1.7.3, Mozilla Firefox 1.0, Netscape 7.2, Apple's Safari 1.2.4, Opera 7.54, and KDE's Konqueror 3.2.2-6. Other versions of these browsers might also be affected. Secunia describes the vulnerabilities as "moderately critical". It advises users not to browse untrusted sites while browsing trusted sites.