I just need to gush for a minute. I am about to shutdown my server in order to move it to the basement. This off the shelf $300 desktop running Pop!_OS is my self-hosting server that has dutifully done it’s job without a single complaint. It has been rebooted maybe three times since 2020 and it currently has an uptime of 840 days. That’s 840 days of not ever thinking about this thing. It self updates via Cron jobs and just…works.
I am afraid to open the box up though. Those dust bunnies must be huge.
How vulnerable your system is with an old kernel/old code depends on what you’re running. If you’re running a bunch of sophisticated services that allow access on the open internet, you may have more vulnerabilities than if you’re just running a file share. The kernel doesn’t really matter at all unless either you allow other people to run commands or someone is able to exploit a RCE exploit.