Update – Please note, this is a beta of the security update for macOS Big Sur, not the final version, at least not yet. It should be available in the next few days, finally, if all goes well.
Apple is starting to hitch the wagons on the train of the latest security updates for macOS. Big Sur users can recover an 11.6.6 which should normally close major flaws. It should be the same, in the short term, for macOS Catalina with a patch probably numbered 2022-004, the 003 being released on March 14.
Details for Big Sur have yet to be posted online, but Apple has addressed two flaws in Monterey that it was careful to point out could have been exploited. One affected AppleAVD, a video decoding system component, and the other involved Intel graphics chip drivers.
Given the critical nature of these flaws, we had expected that all macOS versions still supported would be simultaneously corrected, but macOS Monterey preceded the others by a good week.
Two security holes closed in Monterey, but not in Big Sur or Catalina