# CVE-2021-43405: Command injection in n/a

> Attackers can inject risky characters into the fax_extension field to potentially execute arbitrary commands on the FusionPBX server.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Nov 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-42c2-hjwj-v6gj

## What is CVE-2021-43405?

CVE-2021-43405 is a high-severity command injection vulnerability in Fusionpbx Fusionpbx, published on 5 Nov 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

An issue was discovered in FusionPBX before 4.5.30. The fax_extension may have risky characters (it is not constrained to be numeric).

## Which versions are affected by CVE-2021-43405?

It affects 1 product.


Products: Fusionpbx Fusionpbx.

## How do I fix CVE-2021-43405?

No fix has been published for CVE-2021-43405 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-43405 being exploited?

There is no known exploitation of CVE-2021-43405 in the wild and no public exploit code.

Public exploit code:

- FusionPBX 4.5.29 - Remote Code Execution (RCE) (Authenticated) (exploitdb)

## Other vulnerabilities in Fusionpbx Fusionpbx

- [CVE-2022-35153](https://insights.sbomify.com/CVE-2022-35153/): Command injection in n/a (critical 9.8)
- [CVE-2022-28055](https://insights.sbomify.com/CVE-2022-28055/): Command injection in n/a (critical 9.8)
- [CVE-2021-43404](https://insights.sbomify.com/CVE-2021-43404/): Path traversal in n/a (high 8.8)
- [CVE-2021-43406](https://insights.sbomify.com/CVE-2021-43406/): Other in n/a (high 8.8)
- [CVE-2019-16964](https://insights.sbomify.com/CVE-2019-16964/): Command injection in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43405 and fix it if it is affected.

What it is: CVE-2021-43405 is a high-severity command injection vulnerability in Fusionpbx Fusionpbx, published on 5 Nov 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43405 in the wild and no public exploit code.

Affected product: Fusionpbx Fusionpbx. 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-2021-43405/ (Markdown: https://insights.sbomify.com/CVE-2021-43405/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43405
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43405
- OSV: https://osv.dev/vulnerability/CVE-2021-43405

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43405/
Summaries are generated and may contain mistakes; the official description above is the record.