Intel has released a new round of CPU microcode updates that address the Spectre variant #2 CPU vulnerability that now include older processor microarchitectures (all the way back to Haswell). There is always a delay between when Intel makes these updates available and when the system vendors and motherboard manufacturers do their validation and release BIOS updates.
A number of system vendors and motherboard manufacturers have special sites where you can more easily locate the latest BIOS update for your system. You should make a point of periodically checking to see if any BIOS updates are available for your systems. Here is a list of some of the more popular vendors: