# CVE-2026-74312: vhost/vdpa: validate virtqueue index in mmap and fault paths

> An attacker can trigger an out-of-bounds access in the Linux kernel vhost/vdpa module via mmap or fault paths, potentially causing a crash or 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:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-74312, DEBIAN-CVE-2026-74312, GHSA-vx5g-7fcv-7h84, UBUNTU-CVE-2026-74312

## What is CVE-2026-74312?

CVE-2026-74312 is a high-severity memory corruption 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:

vhost/vdpa: validate virtqueue index in mmap and fault paths

vhost_vdpa_mmap() and vhost_vdpa_fault() use vma->vm_pgoff as a
virtqueue index for get_vq_notification(), but they do not validate
that the index is smaller than v->nvqs.

The ioctl path already performs both a bounds check and
array_index_nospec(), but the mmap/fault path only checks that the
index fits in u16. This allows an out-of-range queue index to reach
driver-specific get_vq_notification() callbacks.

Fix this by extracting a unified vhost_vdpa_get_vq_notification()
helper that validates the queue index against v->nvqs and applies
array_index_nospec() before calling the driver callback. Both the
mmap and fault paths use this helper, and the bounds checking is
consolidated into a single location.

From source inspection, the most defensible impact is out-of-bounds
access in the callback path, potentially leading to invalid PFN
remaps and crash/DoS.

## Which versions are affected by CVE-2026-74312?


## How do I fix CVE-2026-74312?

Apply the vendor's patch.

## Is CVE-2026-74312 being exploited?

There is no known exploitation of CVE-2026-74312 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74312 and fix it if it is affected.

What it is: CVE-2026-74312 is a high-severity memory corruption 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-2026-74312 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-2026-74312/ (Markdown: https://insights.sbomify.com/CVE-2026-74312/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74312
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74312
- OSV: https://osv.dev/vulnerability/CVE-2026-74312

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74312/
Summaries are generated and may contain mistakes; the official description above is the record.