Win10CU is out (officially, unofficial). Not available on Windows Update until next week.
Turns out the earlier links were indeed “RTM”.
I have just download ISO’s from Microsoft using a direct link and using the Media Creation Tool.
Windows 10 download page: https://www.microsoft.com/en-us/software-download/windows10
From Windows click Download Tool Now button.
Tip – I went to this page from Linux and it gave me the option for direct download.
(Click pic for full size.)