eager_eagle comments on Copy Fail (CVE-2026-31431) is a trivially exploitable logic bug in Linux, reachable on all major distros released in the last 9 years. A small, portable python script gets root on all platforms.

[–] eager_eagle@lemmy.world 41 points 4 months ago* (10 children)

wtf

An unprivileged local user can write 4 controlled bytes into the page cache of any readable file on a Linux system, and use that to gain root.

If your kernel was built between 2017 and the patch — which covers essentially every mainstream Linux distribution — you're in scope.

how does that only get a CVE score of 7.8, the impact of this is huge

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[–] Bitflip@lemmy.ml 79 points 4 months ago (8 children)

Probably because the attack vector is having a user account on the target

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[–] nyan@sh.itjust.works 35 points 4 months ago (5 children)

Exactly. It's Yet Another Privilege Escalation Vulnerability. Unless you're dealing with a multiuser machine, the attacker first needs to use some other vuln to get into an unprivileged account. Without that additional vulnerability, this exploit is useless.

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[–] solrize@lemmy.ml 20 points 4 months ago (1 child)

some other vuln

You mean like inveigling it into a pypi or npm or whatever package? Checks out.

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[–] Aatube@piefed.social 16 points 4 months ago

That's privilege escalation for you. 7.8 is pretty high.

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[–] tomalley8342@lemmy.world 5 points 4 months ago* (2 children)

Yet another? Are there really so many LPEVs in linux?

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[–] olosta@lemmy.world 9 points 4 months ago

I manage multi user systems and try to be on top of this and no, privilege escalation with a working public exploit are very rare. There's quite a lot of CVEs with potential privilege excalation, but most of the time there is no real world exploit. And a large part of those are related to user namespaces in one way or another.

This one is truly scary, at least the immediate mitigation is pretty straightforward.

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[–] nyan@sh.itjust.works 6 points 4 months ago

Well, it often feels like every "Linux security issue" flagged in the tech press is a privilege escalation, but I admit that I haven't sat down and done the math.

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