# CVE-2018-4020: Command injection in Netgate pfSense

> Authenticated attackers can execute arbitrary commands via the powerd_ac_mode parameter in the pfSense administration interface.

- **Severity:** High 7.2 (`CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 3 Dec 2018
- **Updated:** 16 Sep 2024
- **Also known as:** GHSA-7fj2-qj5r-2prf

## What is CVE-2018-4020?

CVE-2018-4020 is a high-severity command injection vulnerability in Netgate pfSense, published on 3 Dec 2018. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

An exploitable command injection vulnerability exists in the way Netgate pfSense CE 2.4.4-RELEASE processes the parameters of a specific POST request. The attacker can exploit this and gain the ability to execute arbitrary commands on the system. An attacker needs to be able to send authenticated POST requests to the administration web interface. Command injection is possible in the `powerd_ac_mode` POST parameter parameter.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2018-4020?

It affects 1 product.


Products: Netgate Pfsense.

## How do I fix CVE-2018-4020?

No fix has been published for CVE-2018-4020 yet. Limit exposure of the affected software until one is available.

## Is CVE-2018-4020 being exploited?

There is no known exploitation of CVE-2018-4020 in the wild and no public exploit code.

## Other vulnerabilities in Netgate pfSense

- [CVE-2019-16915](https://insights.sbomify.com/CVE-2019-16915/): Path traversal in n/a (critical 9.8)
- [CVE-2020-21487](https://insights.sbomify.com/CVE-2020-21487/): Cross-site scripting in n/a (critical 9.6)
- [CVE-2024-46538](https://insights.sbomify.com/CVE-2024-46538/): Cross-site scripting in n/a (critical 9.3)
- [CVE-2023-48123](https://insights.sbomify.com/CVE-2023-48123/): Command injection in n/a (high 8.8)
- [CVE-2023-42326](https://insights.sbomify.com/CVE-2023-42326/): Command injection in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-4020 and fix it if it is affected.

What it is: CVE-2018-4020 is a high-severity command injection vulnerability in Netgate pfSense, published on 3 Dec 2018. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-4020 in the wild and no public exploit code.

Affected product: Netgate pfSense. 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-2018-4020/ (Markdown: https://insights.sbomify.com/CVE-2018-4020/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-4020
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-4020
- OSV: https://osv.dev/vulnerability/CVE-2018-4020

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-4020/
Summaries are generated and may contain mistakes; the official description above is the record.