Hi Larry, thanks for following up. I honestly don't understand what's the deal here. I ended up releasing my images on 2021-06-08 with ` allow_unsupported_modules 1 ` in /etc/modprobe.d/10-unsupported-modules.conf . Today I installed it in VirtualBox and commented out the change in 10-unsupported-modules.conf , but this time it still loaded the vboxguest module automatically. Something must have gotten fixed between the time I filed this bug and the date that I generated the ISOs. Sorry for the inconclusive test results.