KB4451762 for Windows 10 1903 and 1909
This update (KB4451762) fixes one thing, which is the SMBv3 security vulnerability, and includes the following highlight:
Updates a Microsoft Server Message Block 3.1.1 protocol issue that provides shared access to files and printers.
And here is the full info on the fix:
Security update to the Microsoft Server Message Block 3.1.1 (SMBv3).
After the update, your version of Windows 10 1903 will be bumped to build 18362.720, and Windows 10 1909 will be bumped to build 18363.720. Note that there is a known issue with this update when using Windows Server containers. Make sure to read the full release notes for all details and workarounds. This update is mandatory, so you should see the new update soon if you have automatic updates enabled on your system. Or, if you can stay on top of things by manually heading to Settings > Update & Security > Microsoft Update to check. Also, keep in mind that this update requires a restart of your system. So, make sure to grab it when you have time to do a reboot or set up Active Hours. Then you can schedule when your PC will restart when you’re not in the middle of working on something. If you have any issues with your PC after installing the update, which isn’t resolved by Microsoft’s documented workarounds, you can roll them back. For more on doing that, check out our article: How to Uninstall a Windows 10 Cumulative Update.