> No bounds check. free_count is incremented before the write, and the write uses the pre-increment value as the index. When free_count == num_niovs at entry, the write goes to freelist[num_niovs], one slot past the end.

"No way to prevent this", Says Only Language Where This Regularly Happens

I can't quite make out if this is new or not. The attack vector here seems congruent with a similar exploit from a couple months ago [1]

But still might be an open threat. On the email thread Jens seems to think that this is already patched and in stable, he also points out that for this exploit to work (as written in the article) you already need escalated privileges [2] Catchy title though.

[1] https://snailsploit.com/security-research/general/io-uring-z...

[2] https://seclists.org/oss-sec/2026/q2/448

What is happening? I see multiple outages and CVEs is being reported on HN's front page. I've never seen these many security/incident related posts on HN's front page.

> “and is writable with CAP_SYS_ADMIN”

Am I reading this wrong or is this just a way of executing an arbitrary binary with uid=0 if you have both CAP_NET_ADMIN and CAP_SYS_ADMIN?

If you can write modprobe_path, is it really news that you can find a way to execute code?

So this is another CVE? Or am I misreading this one? "Copy‑fail", "DirtyFrag", now "IUrinegOnYou :)"?

Joke aside, we'll see more CVEs in the coming months, and in a sense that's good: it leaves less maneuvering room for bad actors (especially those selling them to the highest bidder).

I first read this from the author's posting to oss-security. Turns out that the author did agree to revise the blog post for the "admin cap for root shell" part [^0]. [^1] would probably tell more.

The title looks like clickbait to me.

[^0]: https://www.openwall.com/lists/oss-security/2026/05/08/10

[^1]: https://www.openwall.com/lists/oss-security/2026/05/08/14

This kind of post really shouldn't require client-side js — from third-party domain — to read...

static markdown version: https://raw.githubusercontent.com/ze3tar/ze3tar.github.io/9d...

CAP_NET/SYS_ADMIN is required for this. So this would be "not as bad" as the others.

How many systems have the relevant NICs, and followed the non-automatic setup steps in https://docs.kernel.org/networking/iou-zcrx.html, and are not running within a VM/container disabling io_uring?

This seems on the low impact end of the numerous historical io_uring issues.

Interesting and important all the same.

Interesting, I haven't tested this myself but intuitively I think that a 4 byte OOB write is plenty for a data-only attack like [PageJack](https://i.blackhat.com/BH-US-24/Presentations/US24-Qian-Page...), so I don't think hardening against the KASLR leaks discussed in OP would necessarily save you from this attack.

io-uring is a security nightmare. Constant privescs and a powerful primitive for syscall smuggling. Worth considering disabling it outright (already the case for most containers afaik).

If this many are public right now, what does that say about the dark matter of private ones? What's the typical public-private rate for this sort of thing/can someone help me calibrate my base rate expectations?

Do most servers need this? Or can most of us 'sysctl -w kernel.io_uring_disabled=2 ' ?

What’s our prior for p(doom) today…?

Another one.

Linux is falling apart faster than it can assign these CVEs.