Windows 10 KB4338819 applies to Windows 10 version 1803. This release also contains updates for Microsoft HoloLens (OS Build 17134.165).
- Security updates to Internet Explorer, Windows apps, Windows graphics, Windows datacenter networking, Windows wireless networking, Windows virtualization, Windows kernel, and Windows Server.
- Evaluates the Windows ecosystem to help ensure application and device compatibility for all updates to Windows.
Some other fixes are more concerned with corporate use with virtual machines etc..
A reboot is required to install this update.