[judemelancon]

I think I must misunderstand. Are you saying that you upgrade and reboot every production system that you administer to apply each commit to the kernel (branch it's using) essentially immediately? That doesn't make sense to me for a few reasons, but I struggle to find a different reading that applies "upgrade and reboot on a moment's notice" to the "slipped into mainline linux" scenario. Kindly help me to do so.

[tptacek]

No: your posture with respect to having to cycle servers is a super complicated subject and you address it both with process and with architecture (for instance: you can be blasé about things like CopyFail if you don't allow multitenant shared-kernel in your design in the first place). But no matter what process and design you have, if you're hosting sensitive workloads, you always have to be in a position where you can metabolize having to cycle your servers.

It's a category error to talk about a disclosure event like this as something that would destabilize someone's fleet operations. The Linux kernel is fallible. So is the x64 architecture. You already have to be ready to lock things down and reboot (or mitigate) at a moment's notice.

Remember: whatever else grumpy sysadmins have to say about this, Xint are the good guys. Contrast them with the bad guys, who have vulnerabilities just as bad as CopyFail, but aren't disclosing them at all --- you only find out about them when it's discovered they're actively be exploited. There's no patch at all. There isn't even a characterization of how they work, so that you could quickly see what to seccomp. That's the actual threat environment serious Linux shops operate in.

LPEs are not rare.

[judemelancon]

Oh, I thought you meant "everyone" in a sense including actual human persons and the devices on their home network.

[0x0]

I find it curious to call someone dropping a weaponized root exploit before major distros or even LTS kernel git branches have patches ready "good guys". This could have been handled with much more grace.

[tptacek]

Again: I made the actual distinction between bad guys and good guys clear. Good guys don't become bad guys simply because kernel security is an inconvenience to you.

[eschaton]

There are more than just good guys and bad guys; in particular, there are also opportunists.

Opportunists are the ones who will sell a 0day to bad guys. Or who will drop a 0day publicly to promote their services. And they’ll fight tooth and nail against any actual legal obligation to engage in responsible and coordinated disclosure, because they make more money without that.

[tptacek]

Seems like a classification you just made up to navigate a message board debate: the category that equates commercial vulnerability research for security products and people who sell zero-day vulnerabilities to bad guys.

[eschaton]

People who sell zero-day vulnerabilities currently sell to both good guys and bad guys, they’re a third thing (mercenaries). However, that third thing is also bad, just a different kind of bad than what you’re calling “bad guys.”

The people selling weapons to the Taliban aren’t bad in the same way the Taliban are; one is bad for ideological reasons, the other is bad for enabling bad actors, even if they also sell to the good guys.

[sersi]

To be fair, once Xint gave the heads up and the kernel team committed a patch, what was Xint supposed to do? Keep asking the kernel security team to backport patches for the LTS kernels?

As soon as a patch is committed, the clock starts ticking, the exploit will be discovered by reverse engineering recent commits. The commit was made on April 1st, Xint disclosed it on the 29th. If the Kernel Security team had wanted to, they had 28 days to backport patches in the LTS branches...

So, I wouldn't put any blame on Xint there.

[marshray]

The Linux kernel team back-ported it to 6.18, 6.19, and 7.0 on 2026-04-11 and publicly disclosed the vulnerability via CVE on 2026-04-22.