# 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.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** Yes
- **Published:** 4 Feb 2026
- **Updated:** 19 Oct 2026
- **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, ROOT-OS-DEBIAN-13-CVE-2026-23066, ROOT-OS-UBUNTU-2204-CVE-2026-23066, ROOT-OS-UBUNTU-2404-CVE-2026-23066, UBUNTU-CVE-2026-23066

## 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.

Weakness: CWE-674 (Uncontrolled Recursion), CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-23066?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-23066?

Apply the vendor's patch.

## 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

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23066 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-23066 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-23066/ (Markdown: https://insights.sbomify.com/CVE-2026-23066/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23066
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23066
- OSV: https://osv.dev/vulnerability/CVE-2026-23066

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23066/
Summaries are generated and may contain mistakes; the official description above is the record.