This update will be downloaded and installed automatically from Windows Update. To get the standalone package for this update, go to the Microsoft Update Catalog website.
https://www.catalog.update.microsoft.com/Search.aspx?q=KB4056892
How to Check and Update Windows Systems for the Meltdown and Spectre CPU Flaws
https://www.bleepingcomputer.com/news/microsoft/how-to-check-and-update-windows-systems-for-the-meltdown-and-spectre-cpu-flaws/
January 3, 2018—KB4056892 (OS Build 16299.192) Improvements and fixes
https://support.microsoft.com/en-gb/help/4056892/windows-10-update-kb4056892