# CVE-2021-32847: Moby HyperKit uninitialized memory use in virtio-sock pci_vtsock_proc_tx

> A malicious guest can trigger uninitialized memory use in HyperKit to disclose host memory, requiring a patch to prevent data leakage.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 20 Feb 2023
- **Updated:** 10 Mar 2025
- **Also known as:** GHSA-gpgx-6j76-jh6m

## What is CVE-2021-32847?

CVE-2021-32847 is a high-severity vulnerability in moby hyperkit, published on 20 Feb 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

HyperKit is a toolkit for embedding hypervisor capabilities in an application. In versions 0.20210107 and prior, a malicious guest can trigger a vulnerability in the host by abusing the disk driver that may lead to the disclosure of the host memory into the virtualized guest. This issue is fixed in commit cf60095a4d8c3cb2e182a14415467afd356e982f.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2021-32847?

It affects 1 product.


Products: Mobyproject Hyperkit.

## How do I fix CVE-2021-32847?

No fix has been published for CVE-2021-32847 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-32847 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-32847 exists.

## Other vulnerabilities in moby hyperkit

- [CVE-2021-32845](https://insights.sbomify.com/CVE-2021-32845/): Moby HyperKit uninitialized memory use vtrnd pci_vtrnd_notify (high 7.7)
- [CVE-2021-32846](https://insights.sbomify.com/CVE-2021-32846/): Moby HyperKit uninitialized memory use in virtio-sock pci_vtsock_proc_tx (high 7.7)
- [CVE-2021-32843](https://insights.sbomify.com/CVE-2021-32843/): Null dereference in hyperkit (medium 6.2)
- [CVE-2021-32844](https://insights.sbomify.com/CVE-2021-32844/): Null dereference in hyperkit (medium 6.2)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-32847 and fix it if it is affected.

What it is: CVE-2021-32847 is a high-severity vulnerability in moby hyperkit, published on 20 Feb 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2021-32847 exists.

Affected product: moby hyperkit. 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-2021-32847/ (Markdown: https://insights.sbomify.com/CVE-2021-32847/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32847
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32847
- OSV: https://osv.dev/vulnerability/CVE-2021-32847

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-32847/
Summaries are generated and may contain mistakes; the official description above is the record.