# CVE-2020-3991: Path traversal in VMware Horizon Client for Windows

> An attacker can cause denial of service by overwriting privileged files via symbolic links during installation of VMware Horizon Client for Windows.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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:** 16 Oct 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-6rc8-hqq9-gfph

## What is CVE-2020-3991?

CVE-2020-3991 is a high-severity path traversal vulnerability in VMware Horizon Client for Windows, published on 16 Oct 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

VMware Horizon Client for Windows (5.x before 5.5.0) contains a denial-of-service vulnerability due to a file system access control issue during install time. Successful exploitation of this issue may allow an attacker to overwrite certain admin privileged files through a symbolic link attack at install time. This will result into a denial-of-service condition on the machine where Horizon Client for Windows is installed.

## Which versions are affected by CVE-2020-3991?

It affects 1 product.


Products: Vmware Horizon Client.

## How do I fix CVE-2020-3991?

No fix has been published for CVE-2020-3991 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-3991 being exploited?

There is no known exploitation of CVE-2020-3991 in the wild and no public exploit code.

## Other vulnerabilities in VMware Horizon Client for Windows

- [CVE-2020-3961](https://insights.sbomify.com/CVE-2020-3961/): Privilege escalation in VMware Horizon Client for Windows (high 7.8)
- [CVE-2019-5543](https://insights.sbomify.com/CVE-2019-5543/): Privilege escalation in VMware Horizon Client for Windows (high 7.8)
- [CVE-2018-6964](https://insights.sbomify.com/CVE-2018-6964/): Privilege escalation in Horizon Client for Linux (high 7.8)
- [CVE-2021-21987](https://insights.sbomify.com/CVE-2021-21987/): Information disclosure in VMware Workstation Pro / Player (Workstation), VMware Horizon Client for Windows (medium 6.5)
- [CVE-2021-21988](https://insights.sbomify.com/CVE-2021-21988/): Information disclosure in VMware Workstation Pro / Player (Workstation), VMware Horizon Client for Windows (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-3991 and fix it if it is affected.

What it is: CVE-2020-3991 is a high-severity path traversal vulnerability in VMware Horizon Client for Windows, published on 16 Oct 2020. 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-2020-3991 in the wild and no public exploit code.

Affected product: VMware Horizon Client for Windows. 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-2020-3991/ (Markdown: https://insights.sbomify.com/CVE-2020-3991/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-3991
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-3991
- OSV: https://osv.dev/vulnerability/CVE-2020-3991

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From sbomify Insights: https://insights.sbomify.com/CVE-2020-3991/
Summaries are generated and may contain mistakes; the official description above is the record.