A critical security issue in both Samba (Windows services for Unix/Linux) and Windows will be patched tomorrow, April 12th. This issue is being called “Badlock”. There is some information at http://badlock.org about it now, with more information to be available after the updates are released by the Samba group and Microsoft. You can also expect exploits for this issue to be out shortly after the details of the problem are announced.
Patches will be available for Samba 4.4, Samba 4.3 and Samba 4.2. You can assume that most, if not all, currently supported Windows releases to get this patch too. Please make sure you patch your systems for this issue as soon as possible.