SharePoint 2016 is seeing its first post-go-live update - KB2920721 - available for download here: https://www.microsoft.com/en-us/download/details.aspx?id=51701. You may notice that it doesn't follow the typical CU naming convention of ubersrv* - that's because it's not a cumulative update, but rather just a specific update that contains a single patch sts-x-none.msp.
Things to know about this patch:
- It does not increment the farm's configuration database version. Your previously RTM SP2016 farm (as shown in Central Administration) remains at 16.0.4327.1000 after installing this patch, so you'll need somewhere else like Control Panel --> Programs and Features --> Installed Updates to confirm it's installed.
- As with most other SharePoint updates, you must run the SharePoint Products Configuration Wizard after installing the package itself in order to fully commit the patch installation.
- Also as with most other SharePoint updates, you should be able to extract the .msp patch file to <DriveLetter>:\<SharePointBinaryLocation>\updates (a process called slipstreaming) and use this source when building a new farm from scratch, in order to automatically patch the new farm as it's being built.
- The KB article describing what changes are included in the patch is available at http://support.microsoft.com/kb/2920721.