CVE-2026-23275 io_uring: ensure ctx->rings is stable for task work flags manipulation
A race condition in the Linux kernel io_uring subsystem can occur during ring resizing with specific task run flags, potentially leading to undefined behavior.
- 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-2026-23275?
CVE-2026-23275 is a high-severity vulnerability in Linux kernel, published on 20 Mar 2026. 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: ensure ctx->rings is stable for task work flags manipulation
If DEFER_TASKRUN | SETUP_TASKRUN is used and task work is added while the ring is being resized, it's possible for the OR'ing of IORING_SQ_TASKRUN to happen in the small window of swapping into the new rings and the old rings being freed.
Prevent this by adding a 2nd ->rings pointer, ->rings_rcu, which is protected by RCU. The task work flags manipulation is inside RCU already, and if the resize ring freeing is done post an RCU synchronize, then there's no need to add locking to the fast path of task work additions.
Note: this is only done for DEFER_TASKRUN, as that's the only setup mode that supports ring resizing. If this ever changes, then they too need to use the io_ctx_mark_taskrun() helper.
Weakness: CWE-362
Which versions are affected by CVE-2026-23275?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23275?
Apply the vendor's patch.
Is CVE-2026-23275 being exploited?
There is no known exploitation of CVE-2026-23275 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-23275, DEBIAN-CVE-2026-23275, GHSA-w9fp-2248-jh3m, UBUNTU-CVE-2026-23275.