---
id: CVE-2026-64073
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT

  On PREEMPT_RT, non-HARD irq_work runs in per-CPU kthreads via
  run_irq_workd(), so irq_work_sync() uses …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT

  On PREEMPT_RT, non-HARD irq_work runs in per-CPU kthreads via
  run_irq_workd(), so irq_work_sync() uses …
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 5.16, < 6.1.175'
  - 'linux_kernel >= 6.2, < 6.6.142'
  - 'linux_kernel >= 6.7, < 6.12.92'
  - 'linux_kernel >= 6.13, < 6.18.34'
  - 'linux_kernel >= 6.19, < 7.0.11'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.11
published: '2026-07-19'
updated: '2026-09-03'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64073'
references:
  - url: 'https://git.kernel.org/stable/c/18c0456ea2615b1a743a6db739c74411c3b42bc6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/2dc79362302922cb18f35e262712b5e58de65442'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/684a78183c54c23e70d1cba320f7fc184604210b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/81b582784518196eff1050212a046bc29d3a05dd'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/91840be8f710370607f949a627e070896faeddb8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/eef4f71b46a9929ac33e968538c9dd5d96a02460'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.0018
epssPercentile: 0.06757
ingestedAt: '2026-09-04T05:15:22.660Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

irq_work: Fix use-after-free in irq_work_single() on PREEMPT_RT

On PREEMPT_RT, non-HARD irq_work runs in per-CPU kthreads via
run_irq_workd(), so irq_work_sync() uses rcuwait() to wait for BUSY==0.

After irq_work_single() clears BUSY via atomic_cmpxchg(), it still
dereferences @work for irq_work_is_hard() and rcuwait_wake_up().

An irq_work_sync() caller on another CPU that enters after BUSY is cleared
can observe BUSY==0 immediately, return, and free the work before those
accesses complete — causing a use-after-free.

Fix this by wrapping run_irq_workd() in guard(rcu)() so that the entire
irq_work_single() execution is within an RCU read-side critical
section. Then add synchronize_rcu() in irq_work_sync() after
rcuwait_wait_event() to ensure the caller waits for the RCU grace period
before returning, preventing premature frees.

## Affected

- `linux_kernel >= 5.16, < 6.1.175`
- `linux_kernel >= 6.2, < 6.6.142`
- `linux_kernel >= 6.7, < 6.12.92`
- `linux_kernel >= 6.13, < 6.18.34`
- `linux_kernel >= 6.19, < 7.0.11`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.11`