Installs Cumulative Update on Windows 10 1803.
Does not update other releases of Windows 10 such as 1709, 1703, 1607, 1511, or the Initial release.
A reboot is required but will not be initiated by this deployment, however depending on your environment Windows Update may reboot the computer.
This update may take a very long time to install.
Microsoft has listed known issues for this update. Please see the links below for more details.
Meltdown (CVE-2017-5754) specific information: