The next most severe is Firefox Cross-site IFRAME hijacking where an attack against about :blank frames could allow malicious code execution. Zalewski also published two medium-threat vulnerabilities, one each for Firefox and Internet Explorer. Firefox file prompt delay bypass allows an "attacker to download or run files without user's knowledge or consent." And, finally, Internet Explorer 6 URL bar spoofing is a URL spoofing vulnerability. This last vulnerability does not affect Internet Explorer 7.
Microsoft, Internet Explorer, IE, Firefox, Vulnerabilities