# CVE-2021-26111: Denial of service in Fortinet FortiSwitch

> An attacker on an adjacent network can cause a denial of service by exhausting memory via crafted LLDP/CDP/EDP packets.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **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:** 1 Jun 2021
- **Updated:** 25 Oct 2024
- **Also known as:** GHSA-4mmv-85v4-q6hm

## What is CVE-2021-26111?

CVE-2021-26111 is a medium-severity denial of service vulnerability in Fortinet FortiSwitch, published on 1 Jun 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A missing release of memory after effective lifetime vulnerability in FortiSwitch 6.4.0 to 6.4.6, 6.2.0 to 6.2.6, 6.0.0 to 6.0.6, 3.6.11 and below may allow an attacker on an adjacent network to exhaust available memory by sending specifically crafted LLDP/CDP/EDP packets to the device.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2021-26111?

It affects 1 product.


Products: Fortinet Fortiswitch.

## How do I fix CVE-2021-26111?

No fix has been published for CVE-2021-26111 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-26111 being exploited?

There is no known exploitation of CVE-2021-26111 in the wild and no public exploit code.

## Other vulnerabilities in Fortinet FortiSwitch

- [CVE-2016-4573](https://insights.sbomify.com/CVE-2016-4573/): Auth bypass in n/a (critical 9.8)
- [CVE-2023-37936](https://insights.sbomify.com/CVE-2023-37936/): Hardcoded credentials in FortiSwitch (critical 9.6)
- [CVE-2024-48887](https://insights.sbomify.com/CVE-2024-48887/): Auth bypass in FortiSwitch (critical 9.3)
- [CVE-2023-37937](https://insights.sbomify.com/CVE-2023-37937/): Command injection in FortiSwitch (high 7.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-26111 and fix it if it is affected.

What it is: CVE-2021-26111 is a medium-severity denial of service vulnerability in Fortinet FortiSwitch, published on 1 Jun 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-2021-26111 in the wild and no public exploit code.

Affected product: Fortinet FortiSwitch. 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-2021-26111/ (Markdown: https://insights.sbomify.com/CVE-2021-26111/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-26111
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-26111
- OSV: https://osv.dev/vulnerability/CVE-2021-26111

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-26111/
Summaries are generated and may contain mistakes; the official description above is the record.