# CVE-2026-89901: media: airspy: use vb2_video_unregister_device() on disconnect to fix NULL deref

> A NULL pointer dereference in the Linux kernel airspy driver allows local attackers to cause a system crash by disconnecting the device during streaming.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-101231, BELL-CVE-2026-89901, DEBIAN-CVE-2026-89901, GHSA-wfp4-jcv3-wqgx, UBUNTU-CVE-2026-89901

## What is CVE-2026-89901?

CVE-2026-89901 is a vulnerability in Linux, published on 16 Sep 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:

media: airspy: use vb2_video_unregister_device() on disconnect to fix NULL deref

airspy_disconnect() clears s->udev under v4l2_lock, but
airspy_stop_streaming() unconditionally calls airspy_ctrl_msg() and
airspy_free_stream_bufs() afterwards. If a streaming user closes the
device after disconnect, stop_streaming() runs and dereferences the
NULL s->udev:

  airspy_stop_streaming()
    airspy_ctrl_msg(s, CMD_RECEIVER_MODE, 0, 0, NULL, 0)
      usb_sndctrlpipe(s->udev, 0)         /* NULL deref */
    airspy_free_stream_bufs(s)
      usb_free_coherent(s->udev, ...)     /* NULL deref */

The airspy driver uses vb2_fop_release() in its file_operations, so
replace video_unregister_device(&s->vdev) with
vb2_video_unregister_device(&s->vdev) and move it before clearing
s->udev. vb2_video_unregister_device() releases the vb2 queue, which
synchronously runs airspy_stop_streaming() if streaming is active, so
the URBs, coherent DMA stream buffers and the hardware stop control
message all execute while s->udev is still valid.

vb2_video_unregister_device() locks vdev->queue->lock (vb_queue_lock)
internally, and stop_streaming() locks v4l2_lock, so the previous outer
mutex_lock(&s->vb_queue_lock) / mutex_lock(&s->v4l2_lock) pair around
the unregister sequence would self-deadlock and has been removed. A
short v4l2_lock critical section around s->udev = NULL remains so any
ioctl path that still holds the file descriptor sees coherent state.

Issue identified by automated review of the INV-003 series at
https://sashiko.dev/

## Which versions are affected by CVE-2026-89901?


## How do I fix CVE-2026-89901?

Apply the vendor's patch.

## Is CVE-2026-89901 being exploited?

There is no known exploitation of CVE-2026-89901 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89901 and fix it if it is affected.

What it is: CVE-2026-89901 is a vulnerability in Linux, published on 16 Sep 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-2026-89901 in the wild and no public exploit code.

Affected product: Linux. 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-2026-89901/ (Markdown: https://insights.sbomify.com/CVE-2026-89901/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89901
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89901
- OSV: https://osv.dev/vulnerability/CVE-2026-89901

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89901/
Summaries are generated and may contain mistakes; the official description above is the record.