https://www.bleepingcomputer.com/news/microsoft/windows-10-kb4515384-and-kb4512578-released-with-fixes/

Microsoft is rolling out a new cumulative update to devices with Windows 10 May 2019 Update (version 1903), Windows 10 October 2018 Update (version 1809), and other supported versions with multiple fixes and improvements.

The September 2019 cumulative update for Windows 10 includes security enhancements for Internet Explorer, Microsoft Edge, and input devices such as a mouse, keyboard, or stylus.