# CVE-2009-3726: Null dereference in n/a

> A remote NFS server can cause a Linux kernel panic via a NULL pointer dereference in the NFSv4 client when handling incorrect file attributes.

- **Severity:** High 7.8 (`AV:N/AC:L/Au:N/C:N/I:N/A:C`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Nov 2009
- **Updated:** 7 Aug 2024
- **Also known as:** GHSA-76cp-8jf4-8pv2

## What is CVE-2009-3726?

CVE-2009-3726 is a high-severity vulnerability in Linux kernel, published on 9 Nov 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The nfs4_proc_lock function in fs/nfs/nfs4proc.c in the NFSv4 client in the Linux kernel before 2.6.31-rc4 allows remote NFS servers to cause a denial of service (NULL pointer dereference and panic) by sending a certain response containing incorrect file attributes, which trigger attempted use of an open file that lacks NFSv4 state.

Weakness: CWE-399

## Which versions are affected by CVE-2009-3726?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2009-3726?

Upgrade to a fixed version.

## Is CVE-2009-3726 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2009-3726 exists.

Public exploit code:

- Linux Kernel < 2.6.31-rc4 - 'nfs4_proc_lock()' Denial of Service (exploitdb)

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2009-3726 and fix it if it is affected.

What it is: CVE-2009-3726 is a high-severity vulnerability in Linux kernel, published on 9 Nov 2009. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2009-3726 exists.

Affected product: Linux kernel. 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-2009-3726/ (Markdown: https://insights.sbomify.com/CVE-2009-3726/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2009-3726
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2009-3726
- OSV: https://osv.dev/vulnerability/CVE-2009-3726

---
From sbomify Insights: https://insights.sbomify.com/CVE-2009-3726/
Summaries are generated and may contain mistakes; the official description above is the record.