While some may not have received the March update that would have protected against this, MS have released emergency patches for these OSs.
https://blogs.technet.microsoft.com/msrc/2017/05/12/customer-guidance-for-wannacrypt-attacks/
If they don’t receive them through WUs then they can download direct from –
http://www.catalog.update.microsoft.com/Search.aspx?q=KB4012598