Windows Internet Explorer (formerly Microsoft Internet Explorer; commonly abbreviated to IE), is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems starting in 1995. It was first released as part of the add-on package Plus! for Windows 95 that year. Later versions were available as free downloads, or in service packs, and included in the OEM service releases of Windows 95 and later versions of Windows.
A zero-day exploit is a computer security vulnerability that is being actively practiced before knowledge of the exploit becomes public information. Usually, two groups of experts research and discover new security exploits: those who are interested in fixing the vulnerable software, and those who are interested in exploiting it. Although the companies working to secure the software often have greater funding and closer ties with the software developers, sometimes malicious programmers independently discover software vulnerabilities. These malicious programmers, often erroneously referred to as hackers, release code which exploits the vulnerability before the software developers are made aware of the problem. This 'vulnerability window', the time before software vendors are made aware of the problem and devise a solution, can last from several days to several weeks. The term zero-day refers to the amount of time that systems administrators have to patch susceptible systems after a vulnerability becomes known.
Microsoft says it is working on a fix for the vulnerability, but it does not appear to warrant an out-of-band fix. Microsoft's security update is slated last November 9, 2010 but it does not appear to include a fix for this vulnerability.
Microsoft says it has detected attacks against IE 7.0 but said the "underlying vulnerability" was present in all versions of the browser.
Other browsers, such as Firefox, Opera, Chrome, Safari, are not vulnerable to the flaw Microsoft has identified.