Vulnerability in Kerberos Could Allow Elevation of Privilege.
Microsoft has released an critical update for a vulnerability, that could turn a simple domain user to a domain administrator. This bug affects all the newer versions of Windows Servers, including Server Core.
The only version that are not affected is the Windows RT, probably because has no domain capabilities.
Overview of NVD (National Vulnerability Database):
The Kerberos Key Distribution Center (KDC) in Microsoft Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, and Windows Server 2012 Gold and R2 allows remote authenticated domain users to obtain domain administrator privileges via a forged signature in a ticket, as exploited in the wild in November 2014, aka “Kerberos Checksum Vulnerability.
Read more at MS TechNet site https://technet.microsoft.com/en-us/library/security/MS14-068