# CVE-2026-64424: netpoll: fix a use-after-free on shutdown path

> A use-after-free in the Linux kernel netpoll subsystem allows attackers to cause denial of service or potentially execute code during shutdown.

- **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:** 25 Jul 2026
- **Updated:** 17 Aug 2026
- **Also known as:** AZL-93455, BELL-CVE-2026-64424, DEBIAN-CVE-2026-64424, GHSA-4m75-5382-c595, ROOT-OS-UBUNTU-2204-CVE-2026-64424, UBUNTU-CVE-2026-64424

## What is CVE-2026-64424?

CVE-2026-64424 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jul 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:

netpoll: fix a use-after-free on shutdown path

There is a use-after-free error on netpoll, which is clearly detected by
KASAN.

      BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x3b/0x80
      Read of size 1 at addr ... by task kworker/9:1
      Workqueue: events queue_process
      Call Trace:
       skb_dequeue+0x1e/0xb0
       queue_process+0x2c/0x600
       process_scheduled_works+0x4b6/0x850
       worker_thread+0x414/0x5a0
      Allocated by task 242:
       __netpoll_setup+0x201/0x4a0
       netpoll_setup+0x249/0x550
       enabled_store+0x32f/0x380
      Freed by task 0:
       kfree+0x1b7/0x540
       rcu_core+0x3f8/0x7a0

The problem happens when there is a pending TX worker running in
parallel with the cleanup path.

This is what happens on netpoll shutdown path:

1) __netpoll_cleanup() is called
2) set dev->npinfo to NULL
3) call_rcu() with rcu_cleanup_netpoll_info()
  3.1) rcu_cleanup_netpoll_info() tries to cancel all workers with
       cancel_delayed_work(), but doesn't wait for the worker to finish
4) and kfree(npinfo);

Because 3.1) doesn't really cancel the work, as the comment says "we
can't call cancel_delayed_work_sync here, as we are in softirq", the TX
worker can run after 4).

Tl;DR: queue_process() is not an RCU reader, it reaches npinfo through
the work item via container_of().

Use disable_delayed_work_sync() to ensure the worker is completely
stopped and prevent any future re-arming attempts. Once npinfo is set
to NULL, senders will bail out and not queue new work. The disable flag
ensures any in-flight re-arming attempts also fail silently.

In the future, we can do the cleanup inline here without needing the
npinfo->rcu rcu_head, but that is net-next material.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-64424?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-64424?

Apply the vendor's patch.

## Is CVE-2026-64424 being exploited?

There is no known exploitation of CVE-2026-64424 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-2026-64424 and fix it if it is affected.

What it is: CVE-2026-64424 is a high-severity use after free vulnerability in Linux kernel, published on 25 Jul 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-2026-64424 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-2026-64424/ (Markdown: https://insights.sbomify.com/CVE-2026-64424/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-64424
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-64424
- OSV: https://osv.dev/vulnerability/CVE-2026-64424

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-64424/
Summaries are generated and may contain mistakes; the official description above is the record.