# CVE-2021-3747: MacOS version of Multipass incorrect owner for application directory

> Incorrect file ownership in the macOS Multipass application directory allows local attackers to escalate privileges.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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:** No
- **Published:** 1 Oct 2021
- **Updated:** 17 Sep 2024
- **Also known as:** GHSA-63mg-hhpp-mqfx

## What is CVE-2021-3747?

CVE-2021-3747 is a high-severity vulnerability in Canonical Multipass, published on 1 Oct 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The MacOS version of Multipass, version 1.7.0, fixed in 1.7.2, accidentally installed the application directory with incorrect owner.

Weakness: CWE-732 (Incorrect Permission Assignment for Critical Resource)

## Which versions are affected by CVE-2021-3747?

It affects 1 product.


Products: Canonical Multipass.

## How do I fix CVE-2021-3747?

No fix has been published for CVE-2021-3747 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-3747 being exploited?

There is no known exploitation of CVE-2021-3747 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Multipass

- [CVE-2021-3626](https://insights.sbomify.com/CVE-2021-3626/): Windows version of Multipass unauthenticated localhost tcp control socket can perform mounts (high 8.8)
- [CVE-2026-49238](https://insights.sbomify.com/CVE-2026-49238/): SFTP Server VM Escape in Canonical Multipass (high 8.4)
- [CVE-2026-49237](https://insights.sbomify.com/CVE-2026-49237/): Local Privilege Escalation in Canonical Multipass (high 7.8)
- [CVE-2025-5199](https://insights.sbomify.com/CVE-2025-5199/): LPE on Multipass for macOS (high 7.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3747 and fix it if it is affected.

What it is: CVE-2021-3747 is a high-severity vulnerability in Canonical Multipass, published on 1 Oct 2021. 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-2021-3747 in the wild and no public exploit code.

Affected product: Canonical Multipass. 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-2021-3747/ (Markdown: https://insights.sbomify.com/CVE-2021-3747/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3747
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3747
- OSV: https://osv.dev/vulnerability/CVE-2021-3747

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3747/
Summaries are generated and may contain mistakes; the official description above is the record.