Sources told Krebs on Security that Microsoft is working to patch an "extraordinarily serious" vulnerability, potentially affecting every Windows system released in the last 20 years.
https://www.notebookcheck.net/The-NSA-reports-extraordinarily-serious-Windows-flaw-to-Microsoft-The-US-military-s-already-received-an-update.450232.0.html
This update is available to everyone right now.
For Windows 10 1903 and 1909 the update is KB4528760.
This isn't that surprising considering that Windows 10 is made is Israel. There must be a lot of unpatched backdoors.