# CVE-2021-34420: Zoom Windows installation executable signature bypass

> Attackers can bypass signature verification in the Zoom Windows installer to install malicious software on user computers.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 11 Nov 2021
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-xcgw-94hj-93r7

## What is CVE-2021-34420?

CVE-2021-34420 is a medium-severity vulnerability in Zoom Client for Meetings for Windows, published on 11 Nov 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

The Zoom Client for Meetings for Windows installer before version 5.5.4 does not properly verify the signature of files with .msi, .ps1, and .bat extensions. This could lead to a malicious actor installing malicious software on a customer’s computer.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2021-34420?

It affects 1 product.


Products: Zoom Zoom Client for Meetings.

## How do I fix CVE-2021-34420?

No fix has been published for CVE-2021-34420 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-34420 being exploited?

There is no known exploitation of CVE-2021-34420 in the wild and no public exploit code.

## Other vulnerabilities in Zoom Client for Meetings for Windows

- [CVE-2021-34419](https://insights.sbomify.com/CVE-2021-34419/): HTML injection in Zoom Linux client (low 3.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-34420 and fix it if it is affected.

What it is: CVE-2021-34420 is a medium-severity vulnerability in Zoom Client for Meetings for Windows, published on 11 Nov 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-34420 in the wild and no public exploit code.

Affected product: Zoom Client for Meetings 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-2021-34420/ (Markdown: https://insights.sbomify.com/CVE-2021-34420/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-34420
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-34420
- OSV: https://osv.dev/vulnerability/CVE-2021-34420

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-34420/
Summaries are generated and may contain mistakes; the official description above is the record.