I’ve been running my home lab since 2021 and honestly thought my update routine was solid: apt update && apt upgrade, reboot, job done.
Turns out I was wrong. I was checking CVE‑2026‑31431 (Copy Fail) this morning and realised that despite my “successful” updates, I was still running a vulnerable kernel from March.
I’ve had to rethink how I handle host updates. If you’re relying on a standard upgrade and a reboot to keep Proxmox or Debian hosts safe, you might want to check if yours is lying to you as well.
When a kernel update requires a change in dependencies, something Proxmox kernels do frequently, apt just quietly “keeps back” the package. It doesn’t fail, it doesn’t break the system, and it doesn’t trigger a rollback. It just waits for me to notice.
This should save a click for hopefully everyone.
Yes obviously, if you do not update the packages then they do not get updated.
If you do not read the output of a command then you will not notuce that.
The standard upgrade command has this behavior though, which is unexpected to people like me and the author. You need a specific flag to tell apt to actually upgrade everything which is not the behavior I expected.
But it is clearly stated in the output that it holds back packages.
This is specific to Debian and Ubuntu so why not being more specific in the title?
Thanks for sharing this. I’m very confident with Linux, but I hadn’t thought about this!
Your blog post was concise, too. I hate scrolling forever before finding the solution.
Glad you found it useful. I’m the same, I can’t stand those long posts that make you read a life story before getting to the commands, even worse when a page is riddled by ads or behind a paywall!
I figured if I’d missed it, a few other people probably had too.
