Apple has just released security updates for macOS Catalina and Big Sur. Yes, you saw that right, macOS 10.15 Catalina and 11 Big Sur.

These are formally macOS Big Sur 11.7.11 and Catalina Security Update 2026-001. Although billed as security updates, these extend the security certificates required by iMessage, FaceTime and Mac activation so they will continue working after January 2027. If you’re still running macOS 10.15 or 11, they’re essential. However, there are no published security fixes for either.