# CVE-2026-97988: vhost: invalidate vring access on IOTLB transitions

> A race condition in the Linux kernel vhost driver allows stale ring mappings during IOTLB transitions, potentially leading to code execution or privilege escalation.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Sep 2026
- **Updated:** 21 Oct 2026
- **Also known as:** AZL-104721, BELL-CVE-2026-97988, DEBIAN-CVE-2026-97988, GHSA-xcf7-28q5-2jrx, UBUNTU-CVE-2026-97988

## What is CVE-2026-97988?

CVE-2026-97988 is a 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:

vhost: invalidate vring access on IOTLB transitions

When VIRTIO_F_ACCESS_PLATFORM changes, cached vring pointers and IOTLB
metadata are interpreted in a different address space. Keeping them
across the transition can leave stale ring mappings in use.

Clearing d->iotlb before taking the VQ locks also lets a worker observe
a transient NULL d->iotlb and fall back to d->umem while translating a
descriptor.

Add a common vhost_clear_device_iotlb() helper for vhost-net and
vhost-vsock. Take all VQ mutexes in index order before dropping the
device-wide IOTLB, invalidate each VQ's cached ring access and metadata,
clear pending IOTLB messages, and free the old table after the handoff.
This serializes the transition with workers and prevents mixed address
space mappings.

On the first direct-to-IOTLB transition, invalidate the cached vring
addresses. When an existing device IOTLB is replaced, preserve the
GIOVA ring addresses and reset only the metadata cache. After clearing
ACCESS_PLATFORM, userspace must configure the vring addresses for the
new address mode.

vhost_vq_invalidate_access() clears desc, avail, and used together.
Treat the VQ as invalidated only when all three are NULL, since a single
GIOVA address may legitimately be zero.

## Which versions are affected by CVE-2026-97988?


## How do I fix CVE-2026-97988?

Apply the vendor's patch.

## Is CVE-2026-97988 being exploited?

There is no known exploitation of CVE-2026-97988 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97988 and fix it if it is affected.

What it is: CVE-2026-97988 is a 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-2026-97988 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-2026-97988/ (Markdown: https://insights.sbomify.com/CVE-2026-97988/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97988
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97988
- OSV: https://osv.dev/vulnerability/CVE-2026-97988

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97988/
Summaries are generated and may contain mistakes; the official description above is the record.