# CVE-2021-42755: Integer overflow in Fortinet FortiSwitch, FortiRecorder, FortiVoiceEnterprise, FortiOS, FortiProxy

> An integer overflow in the dhcpd daemon allows unauthenticated network-adjacent attackers to cause a denial of service on Fortinet devices.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:F/RL:U/RC:C`)
- **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:** 18 Jul 2022
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-v985-ffxm-2rhh

## What is CVE-2021-42755?

CVE-2021-42755 is a medium-severity vulnerability in Fortinet Fortios, published on 18 Jul 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An integer overflow / wraparound vulnerability [CWE-190] in FortiSwitch 7.0.2 and below, 6.4.9 and below, 6.2.x, 6.0.x; FortiRecorder 6.4.2 and below, 6.0.10 and below; FortiOS 7.0.2 and below, 6.4.8 and below, 6.2.10 and below, 6.0.x; FortiProxy 7.0.0, 2.0.6 and below, 1.2.x, 1.1.x, 1.0.x; FortiVoiceEnterprise 6.4.3 and below, 6.0.10 and below dhcpd daemon may allow an unauthenticated and network adjacent attacker to crash the dhcpd deamon, resulting in potential denial of service.

Weakness: CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2021-42755?

It affects 5 products.


Products: Fortinet Fortios, Fortinet Fortiproxy, Fortinet Fortirecorder Firmware, Fortinet Fortiswitch, Fortinet Fortivoice.

## How do I fix CVE-2021-42755?

No fix has been published for CVE-2021-42755 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-42755 being exploited?

There is no known exploitation of CVE-2021-42755 in the wild and no public exploit code.

## Other vulnerabilities in Fortinet Fortios

- [CVE-2024-23113](https://insights.sbomify.com/CVE-2024-23113/): Fortinet Multiple Products Format String (critical 9.8, exploited in the wild)
- [CVE-2022-40684](https://insights.sbomify.com/CVE-2022-40684/): Fortinet Multiple Products Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2024-55591](https://insights.sbomify.com/CVE-2024-55591/): Fortinet FortiOS and FortiProxy Authentication Bypass (critical 9.6, exploited in the wild)
- [CVE-2024-21762](https://insights.sbomify.com/CVE-2024-21762/): Fortinet FortiOS Out-of-Bound Write (critical 9.6, exploited in the wild)
- [CVE-2022-42475](https://insights.sbomify.com/CVE-2022-42475/): Fortinet FortiOS Heap-Based Buffer Overflow (critical 9.3, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-42755 and fix it if it is affected.

What it is: CVE-2021-42755 is a medium-severity vulnerability in Fortinet Fortios, published on 18 Jul 2022. 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-2021-42755 in the wild and no public exploit code.

Affected product: Fortinet Fortios. 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-2021-42755/ (Markdown: https://insights.sbomify.com/CVE-2021-42755/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-42755
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-42755
- OSV: https://osv.dev/vulnerability/CVE-2021-42755

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-42755/
Summaries are generated and may contain mistakes; the official description above is the record.