The Safari update released at the same time as the other two updates says it is a patch to mitigate the Spectre vulnerability in OS X 10.11 and macOS 10.12.


On a Mac since 1984.
Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.