# CVE-2026-86566: Dpdk: dpdk: guest with runt rx descriptors underflows copy length in vhost enqueue (split and packed rings)

> A guest with runt RX descriptors can underflow copy length in vhost enqueue, causing denial of service in shared vhost backends.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:N/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:** 14 Oct 2026
- **Updated:** 14 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-86566, GHSA-qff6-4mmg-g5c9, UBUNTU-CVE-2026-86566

## What is CVE-2026-86566?

CVE-2026-86566 is a medium-severity vulnerability in Red Hat Fast Datapath for RHEL 10, published on 14 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A flaw was found in DPDK lib/vhost. A guest with runt RX descriptors can underflow the copy length in vhost enqueue, causing a denial of service in a shared vhost backend such as OVS-DPDK.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound))

## Which versions are affected by CVE-2026-86566?


## How do I fix CVE-2026-86566?

Apply the vendor's patch.

## Is CVE-2026-86566 being exploited?

There is no known exploitation of CVE-2026-86566 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86566 and fix it if it is affected.

What it is: CVE-2026-86566 is a medium-severity vulnerability in Red Hat Fast Datapath for RHEL 10, published on 14 Oct 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-2026-86566 in the wild and no public exploit code.

Affected product: Red Hat Fast Datapath for RHEL 10. 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-2026-86566/ (Markdown: https://insights.sbomify.com/CVE-2026-86566/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86566
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86566
- OSV: https://osv.dev/vulnerability/CVE-2026-86566

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86566/
Summaries are generated and may contain mistakes; the official description above is the record.