According to Microsofts official blog, a security update regarding Winsows update itself is enrolled these days.
The update is applicable to Windows 7 Service Pack 1, Windows Server 2008 R2 Service Pack 1, Windows 8, Windows RT, Windows Server 2012 and the rollout will begin today. Similar to past updates, this update will be automatically installed if Automatic Updates is turned ON, either set to automatically install updates or notify to download/install updates. – Microsoft blog
Details on the changes to the WU/MU client can be found as KB 2887535 at Microsofts knowledge base.