CVE-2025-40047 io_uring/waitid: always prune wait queue entry in io_waitid_wait()
A race condition in the Linux kernel io_uring waitid implementation can lead to denial of service by failing to prune wait queue entries during cancellation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-40047?
CVE-2025-40047 is a high-severity vulnerability in Linux, published on 28 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
io_uring/waitid: always prune wait queue entry in io_waitid_wait()
For a successful return, always remove our entry from the wait queue entry list. Previously this was skipped if a cancelation was in progress, but this can race with another invocation of the wait queue entry callback.
Which versions are affected by CVE-2025-40047?
How do I fix CVE-2025-40047?
Apply the vendor's patch.
Is CVE-2025-40047 being exploited?
There is no known exploitation of CVE-2025-40047 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2025-40047, DEBIAN-CVE-2025-40047, GHSA-2r8v-pxwr-9h89, ROOT-OS-DEBIAN-13-CVE-2025-40047, ROOT-OS-UBUNTU-2404-CVE-2025-40047, UBUNTU-CVE-2025-40047.