The Update Conundrum
the.unknown-universe.co.uk
How a “kept back” Proxmox kernel left my home lab exposed to CVE‑2026‑31431 — why I now check upgradable packages and use apt full‑upgrade.

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.

  • Akrenion@slrpnk.net
    1·
    7 hours ago

    There’s no point in digital hoarding; it just clutters the boot partition and makes future updates messier.

    I feel personally attacked.

  • fratermus@piefed.socialEnglish
    6·
    1 day ago

    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. Since I wasn’t looking at the list of upgradable packages

    Depends on what quietly means. To me it means “with no indication”. Any written warning is quiet, I guess, if one is not reading it.

  • immobile7801@piefed.socialEnglish
    5·
    1 day ago

    I had a similar experience with this vulnerability. I had no idea another command was required to update the kernel. Kind of odd if you ask me, but i’m sure they did it so you’re forced to realize you’re updating the kernel.

  • ShortN0te@lemmy.ml
    243·
    2 days ago

    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.

    • paris@lemmy.blahaj.zone
      182·
      2 days ago

      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.

        • pinball_wizard@lemmy.zip
          11·
          8 hours ago

          Lol.

          Let’s not defend this behavior by apt.

          I’ll die on many “linux is fine for just about everyone” hills.

          Getting apt to actually really honestly - I mean it this time - update everything - isn’t for everyone.

          Some of us just wait for our hardware to break down, and then reinstall the OS, fresh, instead.

          • ShortN0te@lemmy.ml
            1·
            3 hours ago

            Nothing of what you said is on topic. I never said linux is for everyone and so on…

            First, its about server administration. Second, I am neither saying that this behavior is good or bad.

            I am saying that the behavior is clearly stated in the output. Or what else does “packages were held back” mean.

            Blaming ignorance in reading the output prompt on the tools is really childish.

  • Pommes_für_dein_Balg@feddit.org
    82·
    2 days ago

    I’ve been running Debian since 2007 and never understood the point of apt upgrade .
    When I update, I want the updated version for everything on my system.
    I don’t want to arbitrarily hold back packages just because a dependency changed. I’ll decide for myself if that’s an issue in my deployment. And Debian is generally very good at keeping everything running exactly the same way between releases.

    I pin the release by name (not “stable”) and then apt dist-upgrade always.

    • TheIPW@lemmy.mlOP
      51·
      2 days ago

      No, apt isn’t just a rename. apt upgrade largely replaces apt-get upgrade, but it’s a bit more aggressive: it may install new packages if required as dependencies (it still won’t remove packages). If an upgrade needs to remove packages to resolve dependencies, use apt full-upgrade (same as apt-get dist-upgrade).

  • actionjbone@sh.itjust.works
    12·
    2 days ago

    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.

    • TheIPW@lemmy.mlOP
      6·
      2 days ago

      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.

  • hendrik@palaver.p3x.deEnglish
    6·
    2 days ago

    Shouldn’t the upgrade also update the bootloader’s default entry to a new kernel? The way I’ve been doing it was apt update && apt dist-upgrade. And then reboot once every 1 to 2 years if I feel like it, am bored, or there’s all these news articles about a severe bug in the kernel.