Took me a second to check but
Windows 10 22H2 x64, which is probably what most Windows 10 users are on: KB5041580
Windows 11 23H2 x64, which is what I imagine most windows 11 users are on: KB5041585
If you, like me, have not had to actually check on your installed windows updates since the Windows 7 days, System Settings -> Check for Updates -> View Update History, should be sorted with most recent at the top, and in my case this was the first one in the list.
If you're using something else here's the list of Windows Updates you can look at: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-38063