Severity Rating: Critical
Revision Note: V1.1 (February 28, 2014): Bulletin revised to announce a detection change in the 2900986 update for Windows 8.1 for 32-bit Systems, Windows 8.1 for x64-based Systems, Windows RT 8.1, and Windows Server 2012 R2. This is a detection change only. There were no changes to the update files. Customers who have already successfully updated their systems do not need to take any action.
Summary: This security update resolves a privately reported vulnerability that is currently being exploited. The vulnerability exists in the InformationCardSigninHelper Class ActiveX control. The vulnerability could allow remote code execution if a user views a specially crafted webpage with Internet Explorer, instantiating the ActiveX control. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.