# CVE-2026-97996: virtio: fix use-after-free in unregister_virtio_device()

> A use-after-free in the Linux kernel virtio subsystem allows local attackers to potentially execute code or escalate privileges when unbinding specific virtio devices.

- **Severity:** Not scored
- **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 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-97996, DEBIAN-CVE-2026-97996, GHSA-gfg9-4r2g-565g, UBUNTU-CVE-2026-97996

## What is CVE-2026-97996?

CVE-2026-97996 is an use after free vulnerability in Linux, published on 25 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:

virtio: fix use-after-free in unregister_virtio_device()

device_unregister() is device_del() plus put_device(). When the caller
holds no extra reference, that drops the last one and runs the release
callback, which for several transports frees the memory the embedded
struct virtio_device sits in. unregister_virtio_device() then calls
virtio_debug_device_exit(), which reads dev->debugfs_dir out of the freed
object.

Affected transports are the ones whose release callback frees and whose
remove path takes no reference: virtio_mmio, virtio_vdpa, virtio_uml,
mlxbf-tmfifo and virtio_ccw. virtio_pci is unaffected because
virtio_pci_remove() brackets the call with get_device() and put_device().

Remove the debugfs entries before the device can go away. They are only
accessed through the protected debugfs interface, so
debugfs_remove_recursive() waits for in-progress file operations before
returning. Tearing them down while the device is still alive is therefore
safe.

Reproduced on User-Mode Linux with CONFIG_KASAN and CONFIG_VIRTIO_DEBUG
by unbinding a virtio-uml device:

  BUG: KASAN: slab-use-after-free in virtio_debug_device_exit+0x36/0x4d
  Read of size 8 at addr 00000000616e0b10 by task init/1
   __asan_report_load8_noabort
   virtio_debug_device_exit+0x36/0x4d
   unregister_virtio_device+0x48/0x75
   virtio_uml_remove
   platform_remove
   device_release_driver_internal
   unbind_store

  Freed by task 1:
   kfree
   virtio_uml_release_dev
   device_release
   kobject_put
   put_device
   device_unregister

With this applied, the report is gone and unbind is clean.

## Which versions are affected by CVE-2026-97996?


## How do I fix CVE-2026-97996?

Apply the vendor's patch.

## Is CVE-2026-97996 being exploited?

There is no known exploitation of CVE-2026-97996 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97996 and fix it if it is affected.

What it is: CVE-2026-97996 is an use after free vulnerability in Linux, published on 25 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-2026-97996 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-2026-97996/ (Markdown: https://insights.sbomify.com/CVE-2026-97996/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97996
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97996
- OSV: https://osv.dev/vulnerability/CVE-2026-97996

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97996/
Summaries are generated and may contain mistakes; the official description above is the record.