# CVE-2023-6660: NFS client data corruption and kernel memory disclosure

> An unprivileged user can trigger NFS client bugs to disclose sensitive kernel memory or corrupt data written to NFS mounts.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **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:** 13 Dec 2023
- **Updated:** 13 Feb 2025
- **Also known as:** GHSA-cvh9-m5vp-qhrv

## What is CVE-2023-6660?

CVE-2023-6660 is a medium-severity vulnerability in Freebsd Freebsd, published on 13 Dec 2023. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

When a program running on an affected system appends data to a file via an NFS client mount, the bug can cause the NFS client to fail to copy in the data to be written but proceed as though the copy operation had succeeded.  This means that the data to be written is instead replaced with whatever data had been in the packet buffer previously.  Thus, an unprivileged user with access to an affected system may abuse the bug to trigger disclosure of sensitive information.  In particular, the leak is limited to data previously stored in mbufs, which are used for network transmission and reception, and for certain types of inter-process communication.

The bug can also be triggered unintentionally by system applications, in which case the data written by the application to an NFS mount may be corrupted.  Corrupted data is written over the network to the NFS server, and thus also susceptible to being snooped by other hosts on the network.

Note that the bug exists only in the NFS client; the version and implementation of the server has no effect on whether a given system is affected by the problem.

## Which versions are affected by CVE-2023-6660?

It affects 1 product.


Products: Freebsd Freebsd.

## How do I fix CVE-2023-6660?

No fix has been published for CVE-2023-6660 yet. Limit exposure of the affected software until one is available.

## Is CVE-2023-6660 being exploited?

There is no known exploitation of CVE-2023-6660 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-2023-6660 and fix it if it is affected.

What it is: CVE-2023-6660 is a medium-severity vulnerability in Freebsd Freebsd, published on 13 Dec 2023. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-6660 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-2023-6660/ (Markdown: https://insights.sbomify.com/CVE-2023-6660/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-6660
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-6660
- OSV: https://osv.dev/vulnerability/CVE-2023-6660

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-6660/
Summaries are generated and may contain mistakes; the official description above is the record.