Install for ZombieLoad Fix
Every update includes security fixes, but some are bigger than others and deserve a specific call out. This is one of those cases. The Zombieload bug essentially affects every Mac from 2011 on with an Intel processor.
It's similar to the Spectre and Meltdown attacks we've seen in the past and is made up of four bugs strung together. The good news is that this isn't an easy attack, but it is still an issue.
This attack can basically bring your private browsing history back to life as well as other sensitive information based on a description from CPU.fail. This problem can impact macOS, virtual machines in the cloud and trusted environments.
This is a major reason you should install macOS 10.14.5 on your computer today. This is included in 10.14.6.