# CVE-2020-7462: Use after free in FreeBSD

> A use-after-free bug in the FreeBSD kernel allows attackers to cause a kernel panic via crafted IPv6 packets on the loopback interface.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 26 Mar 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-vfw2-5cx4-6c4q

## What is CVE-2020-7462?

CVE-2020-7462 is a medium-severity use after free vulnerability in Freebsd Freebsd, published on 26 Mar 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In 11.4-PRERELEASE before r360733 and 11.3-RELEASE before p13, improper mbuf handling in the kernel causes a use-after-free bug by sending IPv6 Hop-by-Hop options over the loopback interface. The use-after-free situation may result in unintended kernel behaviour including a kernel panic.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2020-7462?

It affects 1 product.


Products: Freebsd Freebsd.

## How do I fix CVE-2020-7462?

No fix has been published for CVE-2020-7462 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-7462 being exploited?

There is no known exploitation of CVE-2020-7462 in the wild and no public exploit code.

## 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-2020-7462 and fix it if it is affected.

What it is: CVE-2020-7462 is a medium-severity use after free vulnerability in Freebsd Freebsd, published on 26 Mar 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-2020-7462 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-2020-7462/ (Markdown: https://insights.sbomify.com/CVE-2020-7462/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-7462
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-7462
- OSV: https://osv.dev/vulnerability/CVE-2020-7462

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-7462/
Summaries are generated and may contain mistakes; the official description above is the record.