Well my Windows and Macintosh InDesign sub-version is 18.104.22.168
Both Win & Mac CC apps say I am up to date.
-- but in Announcement above I see a reference to CC 2015.4.1
With this update, we have fixed bugs and crashes discovered after we released Adobe InDesign CC 2015.4
Here is the Release Notes link for this update https://helpx.adobe.com/indesign/release-note/indesign-cc-2015-11-4-1.html
And I am having crashes over the net - item #1 in the release notes above.
CC 2015 is InDesign version 11....
In the crazy system of Adobe numbering, both of those numbers are correct. The Marketing people call it InDesign CC 2015.4.
But the engineers count versions from version 1. This is version 11. And the build version is 22.214.171.124. (That's because we've had releases for 11.1, 11.2, 11.3 and 11.4. There was a bug fix to 11.4.1.)
The splash screen shows both systems: