Microsoft has released an out-of-band patch for vulnerability MS14-068.
This vulnerability is rated as critical and could allow for escalation of privileges.
System owners are advised to patch their Domain Controller servers as soon as possible.
Microsoft has advised that all Windows servers should be patched as a precaution, however the Domain Controller servers are significantly higher priority.
Recommended Link
http://blogs.technet.com/b/srd/archive/2014/11/18/additional-information-about-cve-2014-6324.aspx
Other Links
Microsoft Security Bulletin:
https://technet.microsoft.com/en-us/library/security/MS14-068