Are macos Mojave Security Updates Cumulative? I had upgraded to macOS Mojave on April 2020 and am still on it.
The Software Installations list on System Information lists the following security updates installed:

Security Update 2020-002
Security Update 2020-003
Security Update 2020-004
Security Update 2020-005
Security Update 2020-006

As you can see Security Update 2020-001, which was released on January 28, 2020 is missing from the list. I don't recall if I installed 2020-002 security update manually on it or through Software Update.
Now that Apple is releasing even Combo updates for the macOS, which are cumulative updates of point releases, is there any clarity on whether security updates are also now cumulative?
Yes, security updates are cumulative since the most recent point release. So, if you're downloading updates manually (to use with offline machines, or in some sort of automated deployment setup, etc), you'll want to install (1) the most recent &quot;combo update&quot; followed by (2) the most recent &quot;security update&quot;.
Frustratingly, I have been unable to find any official confirmation of this from Apple, but I am relatively confident this is how things work based on my own use. If you try to install an OS X 10.9.5 security update (like 2016-004) before updating from 10.9.4 to 10.9.5, the installer will complain and won't run. However, installing security update 2016-001 followed by 2016-004 seems to have the same affect as just installing 2016-004—you end up on the same build version.