# CVE-2026-74311: virtio: rtc: tear down old virtqueues before restore

> A null pointer dereference in the Linux kernel virtio RTC driver during device restore can crash the guest kernel, causing a denial of service.

- **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:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-74311, DEBIAN-CVE-2026-74311, GHSA-4fvg-c4gx-gxg2, UBUNTU-CVE-2026-74311

## What is CVE-2026-74311?

CVE-2026-74311 is a high-severity vulnerability in Linux, published on 15 Aug 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: rtc: tear down old virtqueues before restore

virtio_device_restore() resets the device and restores the negotiated
features before calling ->restore(). viortc_freeze() intentionally
leaves the existing virtqueues in place so the alarm queue can still
wake the system, but viortc_restore() immediately calls
viortc_init_vqs() without first deleting those old queues.

If virtqueue reinitialization fails on virtio-pci, the transport error
path can run vp_del_vqs() against a newly allocated vp_dev->vqs array
while vdev->vqs still contains the old virtqueues. vp_del_vqs() then
looks up queue state through the new array and can dereference a NULL
info pointer in vp_del_vq(), crashing the guest kernel during restore.

This can also happen during a non-faulty reinitialization, when one of
the vp_find_vqs_msix() attempts is unsuccessful before a later attempt
would succeed.

Delete the stale virtqueues before rebuilding them. If restore fails
before virtio_device_ready(), reuse the remove path to stop the device.
Once the device is ready, return errors directly instead of deleting the
virtqueues again.

## Which versions are affected by CVE-2026-74311?


## How do I fix CVE-2026-74311?

Apply the vendor's patch.

## Is CVE-2026-74311 being exploited?

There is no known exploitation of CVE-2026-74311 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74311 and fix it if it is affected.

What it is: CVE-2026-74311 is a high-severity vulnerability in Linux, published on 15 Aug 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-2026-74311 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-2026-74311/ (Markdown: https://insights.sbomify.com/CVE-2026-74311/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74311
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74311
- OSV: https://osv.dev/vulnerability/CVE-2026-74311

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74311/
Summaries are generated and may contain mistakes; the official description above is the record.