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by bjackman 43 days ago
It's not RCE it's an LPE in an obscure corner of the kernel attack surface that no sensible application depends on. They are absolutely a dime a dozen.

Even just in AF_ALG there have been several such vulns fixed in 2026 already. Kernel wide probably hundreds. It's true that most of them will be harder to exploit than this one but that just means you need to prompt your AI a bit harder to get an exploit. (To be fair, in a lot of cases it's gonna be hard to escalate privs without crashing the machine).

Ubuntu has userns restrictions now which takes away the main sources of LPEs (random qdiscs, nftables, all that garbage) but there are still huge numbers of these vulns. This is why platforms that do native untrusted code executions have extreme sandboxing. Note Android and ChromeOS aren't affected coz they already knew this code was broken and hide it from unpriv workloads.

You can't run untrusted code on Linux without either a very very carefully designed sandboxing layer (like Android/ChromeOS) or virtualization. copy.fail is just one among tens of thousands of reasons for this, and it's a pretty uninteresting one at that.

What is "special" depends on your usecase but for my job it's mostly about stuff that's exposed to KVM guests. Biggest source of concerning vulns for us is probably vhost. I expect there are also lots of undiscovered and scary vulns in places like virtiofs, vfio, DAX, and wherever we do device passthrough.

> I could find any places running containered services and exfiltrate secrets parallel services, no?

Yes. Regardless of copy.fail. Cloud providers don't do that without a VM layer. (If yours does, you need to switch).

1 comments

The cope of some people is insane. Why even have UID:GID? All you need is 0:0. I always tell people to run everything as root because there is literally no point.
Well, there's still value in users and namespaces! Just, it's not a strong security boundary.

Also even if it's not strong, it doesn't mean it's entirely worthless. You can't rely on it, but it's usually free and it still buys you time / increases attack cost.

Like, if you leave 100k cash in a car on the street in SF, that's dumb. If you really need to do that for some strange reason, you should hire a security guard to watch your car, because cars a not a good security boundary. BUT, that doesn't mean you would leave the car unlocked just coz someone's watching it!