Embargo is lifted, the dbxupdate is now available from uefi.org. One can drop it into /usr/share/secureboot/updates/dbx/ and trigger reinstall of secureboot-db package to observe that dbx update fails to apply on 2MB firmware, but should work on the 4MB firmware.
There are update securebootdb packages available from a PPA too, I will make them available tomorrow.
Embargo is lifted, the dbxupdate is now available from uefi.org. One can drop it into /usr/share/ secureboot/ updates/ dbx/ and trigger reinstall of secureboot-db package to observe that dbx update fails to apply on 2MB firmware, but should work on the 4MB firmware.
There are update securebootdb packages available from a PPA too, I will make them available tomorrow.