There have been stories about this kind of certificate expiration before that turned out to be nothingburgers, incluing almost a year ago (https://lwn.net/Artic

There have been stories about this kind of certificate expiration before that turned out to be nothingburgers, incluing almost a year ago (https://lwn.net/Articles/1029767/ https://lwn.net/Articles/1029767/). Mint has already fixed the issue for me; my one boot key shows as being issued by Canonical and not expiring until 2042. The forums are full of people suggesting to disable secure boot at installation anyway; I didn't even know about it at the time I installed, and never had a problem. For that matter, there are people successfully running new Linux on machines older than the expiring keys. Incidentally, `mokutil --sb-state` (and `--list-enrolled`) doesn't require root, at least on my system.