https://www.bleepingcomputer.com/news/microsoft/windows-10-update-kb4482887-released-with-performance-fix-for-spectre-bug/

Microsoft has released the Windows 10 KB4482887 cumulative update for build 1809 that includes numerous fixes including Retpoline Spectre mitigation, a fix for an annoying Action Center bug, and numerous other bug fixes.

This update is available to all Windows 10 October 2018 Update (build 1809) users and can be installed through Windows Update. To install the update, simply go into Settings -> Update & Security -> Windows Update and then check for new updates.