Internet Explore 8 Beta 2, the latest developmental milestone of the next iteration of Microsoft's proprietary browser, is safe from the Critical vulnerabilities impacting its precursors, which the company patched on December 9. In this context, the Microsoft Security Bulletin MS08-073 (Critical) does not deliver security updates for IE8 Beta. The Cumulative Security Update for Internet Explorer is only valid for the supported versions of older editions of Internet Explorer.

“This security update is rated Critical for Internet Explorer 5.01 and Internet Explorer 6 Service Pack 1, running on Microsoft Windows 2000; Internet Explorer 6 running on Windows XP; and Internet Explorer 7. For Internet Explorer 6 running on Windows Server 2003, this security update is rated Moderate. Beta versions of Internet Explorer are not vulnerable,” Terry McCoy, program manager, Internet Explorer Security, explained.

According to Microsoft, even the copies of IE7 running on top of Windows XP SP3 (impacted by two Critical vulnerabilities) and Windows Vista SP1 (also impacted by two Critical security flaws) are affected.

The HTML Objects Memory Corruption vulnerability and the Uninitialized Memory Corruption one affect only IE7, while the Parameter Validation Memory Corruption vulnerability and the HTML Rendering Memory Corruption one only affect older versions of the browser. The security bulletin has been released as a part of the monthly Microsoft patch cycle, and is available via Windows Update. The Redmond company emphasized that all four vulnerabilities had been privately reported.

“This update addresses four remote code execution vulnerabilities. The security update addresses these vulnerabilities by modifying the way that Internet Explorer validates parameters, handles the error resulting in the exploitable condition, and handles extra data when embedding objects in Web pages,” McCoy added. “IE security updates are cumulative and contain all previously released updates for each version of Internet Explorer.”

Internet Explorer 8 (IE8) Beta 2 is available for download here.