Microsoft has issued an emergency fix for a vulnerability in Windows Kerberos that is being actively exploited via in-the-wild attacks that target Windows Server 2008 and 2008 R2. The vulnerability could allow an attacker to remotely gain administrator-level privileges. Microsoft has rated the vulnerability as “critical” for servers, and says it affects all supported versions of Windows Server 2003, 2008, 2008. Microsoft also issuing a related update “on a defense-in-depth basis” for Windows Vista, Windows 7, Windows 8, and Windows 8.1″”]
Source: https://www.govinfosecurity.com/microsoft-sounds-zero-day-warning-a-7579