VMware released a new update for the Windows based vCenter Server as well as for the Appliance 6.5. This new version is called 18.104.22.16800 Build 7515524 and is instantly available.
It is also a part of fixing the Spectre & Meltdwon issue.
You can download all needed files here:
How to update the Appliance? See my latest post -> Update VCSA 6.5