# CVE-2021-43204: Denial of service in Fortinet FortiClientWindows

> An attacker can cause a complete denial of service of FortiClient Windows components by manipulating directory access permissions.

- **Severity:** Medium 4.4 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H/E:F/RL:O/RC:C`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Dec 2021
- **Updated:** 25 Oct 2024
- **Also known as:** GHSA-fqqh-g3vm-m5g2

## What is CVE-2021-43204?

CVE-2021-43204 is a medium-severity denial of service vulnerability in Fortinet Forticlient, published on 9 Dec 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A improper control of a resource through its lifetime in Fortinet FortiClientWindows version 6.4.1 and 6.4.0, version 6.2.9 and below, version 6.0.10 and below allows attacker to cause a complete denial of service of its components via changes of directory access permissions.

## Which versions are affected by CVE-2021-43204?

It affects 1 product.


Products: Fortinet Forticlient.

## How do I fix CVE-2021-43204?

No fix has been published for CVE-2021-43204 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-43204 being exploited?

There is no known exploitation of CVE-2021-43204 in the wild and no public exploit code.

## Other vulnerabilities in Fortinet Forticlient

- [CVE-2019-17658](https://insights.sbomify.com/CVE-2019-17658/): Privilege escalation in Fortinet FortiClientWindows (critical 9.8)
- [CVE-2023-45590](https://insights.sbomify.com/CVE-2023-45590/): Code injection in FortiClientLinux (critical 9.4)
- [CVE-2017-14184](https://insights.sbomify.com/CVE-2017-14184/): Information disclosure in FortiClient SSLVPN Client for Linux (high 8.8)
- [CVE-2016-8493](https://insights.sbomify.com/CVE-2016-8493/): Privilege escalation in Fortinet FortiClient (high 8.8)
- [CVE-2020-15934](https://insights.sbomify.com/CVE-2020-15934/): Privilege escalation in FortiClientLinux (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43204 and fix it if it is affected.

What it is: CVE-2021-43204 is a medium-severity denial of service vulnerability in Fortinet Forticlient, published on 9 Dec 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-2021-43204 in the wild and no public exploit code.

Affected product: Fortinet Forticlient. 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-2021-43204/ (Markdown: https://insights.sbomify.com/CVE-2021-43204/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43204
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43204
- OSV: https://osv.dev/vulnerability/CVE-2021-43204

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43204/
Summaries are generated and may contain mistakes; the official description above is the record.