How can I list all updates installed on Mac OS X?
Do not rely on AppStore to tell you if you have the latest updates installed. It will lie to you.
Open the Terminal application and type the following and hit enter:
Shows the Mac OS install history, including updates. By default, only displays updates installed by
softwareupdate. To see all installs including Applications type the following and hit enter:
softwareupdate --history --all
Not sure if this works on older MacOS releases, but it works for High Sierra as of 10.13.4.