# CVE-2020-7461: Memory corruption in FreeBSD

> A heap overflow in FreeBSD's dhclient allows remote code execution via malformed DHCP options, though limited by sandboxing.

- **Severity:** High 7.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Mar 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-x566-m9mc-f47w

## What is CVE-2020-7461?

CVE-2020-7461 is a high-severity memory corruption vulnerability in Freebsd Freebsd, published on 26 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In FreeBSD 12.1-STABLE before r365010, 11.4-STABLE before r365011, 12.1-RELEASE before p9, 11.4-RELEASE before p3, and 11.3-RELEASE before p13, dhclient(8) fails to handle certain malformed input related to handling of DHCP option 119 resulting a heap overflow. The heap overflow could in principle be exploited to achieve remote code execution. The affected process runs with reduced privileges in a Capsicum sandbox, limiting the immediate impact of an exploit.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2020-7461?

It affects 3 products.


Products: Freebsd Freebsd, Siemens Simatic Rf350m Firmware, Siemens Simatic Rf650m Firmware.

## How do I fix CVE-2020-7461?

No fix has been published for CVE-2020-7461 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-7461 being exploited?

There is no known exploitation of CVE-2020-7461 in the wild and no public exploit code.

Public exploit code:

- PoC for DHCP vulnerability (NAME:WRECK) in FreeBSD (github_poc): https://github.com/knqyf263/CVE-2020-7461
- Reproducer PoC for FreeBSD dhclient heap-based buffer overflow vulnerability when parsing DHCP option 119 (CVE-2020-7461) (github_poc): https://github.com/0xkol/freebsd-dhclient-poc

## Other vulnerabilities in Freebsd Freebsd

- [CVE-2018-17160](https://insights.sbomify.com/CVE-2018-17160/): Memory corruption in FreeBSD (critical 10.0)
- [CVE-2014-3954](https://insights.sbomify.com/CVE-2014-3954/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-4304](https://insights.sbomify.com/CVE-2006-4304/): Memory corruption in n/a (critical 10.0)
- [CVE-2006-0226](https://insights.sbomify.com/CVE-2006-0226/): Integer overflow in n/a (critical 10.0)
- [CVE-2004-0002](https://insights.sbomify.com/CVE-2004-0002/): Denial of service in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-7461 and fix it if it is affected.

What it is: CVE-2020-7461 is a high-severity memory corruption vulnerability in Freebsd Freebsd, published on 26 Mar 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-7461 in the wild and no public exploit code.

Affected product: Freebsd Freebsd. 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-2020-7461/ (Markdown: https://insights.sbomify.com/CVE-2020-7461/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-7461
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-7461
- OSV: https://osv.dev/vulnerability/CVE-2020-7461

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-7461/
Summaries are generated and may contain mistakes; the official description above is the record.