hoakley Macs, Technology

Firmware updates for macOS Tahoe, Sequoia and Sonoma

Of all the important features of Macs, firmware must be among the dullest, although it’s also one of the Mac’s major benefits. Because Mac hardware, firmware, and its operating system are all made by Apple, the firmware in our Macs should always remain secure, robust and up to date.

That wasn’t always the case, though. Older Intel Macs could be difficult and sometimes impossible to update their firmware. Some particular configurations were notorious, and most became unreliable if you replaced their internal storage. After a long campaign with tools like eficheck, switching first to T2 then Apple silicon chips has proved decisive. With firmware updates distributed in and installed by macOS updates and upgrades, it’s almost unheard of now for a recent model to be running out of date firmware, unless it’s also running out of date macOS.

This has been important for system stability, where flaws in firmware can turn the most stable Mac into a series of kernel panics and crashes, and essential for security. All the user has to do to secure their Mac’s firmware is to keep macOS up to date. Vulnerabilities in PC firmware are relatively frequent and notoriously hard to address.

Now that support for Intel Macs is waning, and there are only a couple of iMac variants lacking T2 chips that are still fully supported, keeping track of firmware updates is far simpler. Last week’s release of macOS updates brought firmware updates all round, for the iMac19,1 and iMac19,2, as well as T2 and Apple silicon models.

The iMac19,1 and iMac19,2 (4K and 5K 2019) have firmware updates to take them from 2075.100.3.0.3 to 2094.80.5.0.0, the same EFI version found in T2 models. That’s the first update for them since last Spring (March).

Intel models with T2 chips have the same EFI version update to 2094.80.5.0.0, as well as their iBridge firmware, which changes from 23.16.12048.0.0,0 to 23.16.13120.0.0,0.

Currently all Apple silicon Macs from the first base M1 to those with the latest M4 and M5 chips, run common firmware, and that too has been updated from 13822.61.10 to 13822.81.10.

Version numbering of iBoot in Apple silicon Macs seems to have stabilised, with

  • A major version number set by the current major macOS. For macOS 14 that was 10151, for macOS 15 it was 11881, and for macOS 26 it’s currently 13822.
  • A minor version number that increments for each minor version of macOS. This runs in the sequence 1 (macOS x.0), 41 (x.1), 61 (x.2), 81 (x.3), 101 (x.4), 121 (x.5) and 141 (x.6).
  • A patch version number that varies from 1-10, and has once reached 96.

The iBoot update released with security updates to the older two supported versions of macOS should be the same as that for the current version. Thus, the next iBoot update should bring its version number to 13822.101.x, in macOS 26.4, 15.7.5 and 14.8.5. We’ll see how close that gets.

I maintain separate lists of current firmware versions for all three supported versions of macOS: