CVE-2026-23066 rxrpc: Fix recvmsg() unconditional requeue
A flaw in the Linux kernel's rxrpc module allows queue corruption leading to use-after-free, potentially enabling code execution or privilege escalation.
- 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-2026-23066?
CVE-2026-23066 is a high-severity use after free vulnerability in Linux kernel, published on 4 Feb 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:
rxrpc: Fix recvmsg() unconditional requeue
If rxrpc_recvmsg() fails because MSG_DONTWAIT was specified but the call at the front of the recvmsg queue already has its mutex locked, it requeues the call - whether or not the call is already queued. The call may be on the queue because MSG_PEEK was also passed and so the call was not dequeued or because the I/O thread requeued it.
The unconditional requeue may then corrupt the recvmsg queue, leading to things like UAFs or refcount underruns.
Fix this by only requeuing the call if it isn't already on the queue - and moving it to the front if it is already queued. If we don't queue it, we have to put the ref we obtained by dequeuing it.
Also, MSG_PEEK doesn't dequeue the call so shouldn't call rxrpc_notify_socket() for the call if we didn't use up all the data on the queue, so fix that also.
Which versions are affected by CVE-2026-23066?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-23066?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-23066 being exploited?
There is no known exploitation of CVE-2026-23066 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-77250, BELL-CVE-2026-23066, DEBIAN-CVE-2026-23066, GHSA-rx25-rppp-x99w, ROOT-OS-DEBIAN-11-CVE-2026-23066, ROOT-OS-DEBIAN-12-CVE-2026-23066 and 4 more.