# CVE-2023-6356: Kernel: null pointer dereference in nvmet_tcp_build_iovec

> An unauthenticated attacker can cause a kernel panic and denial of service by sending crafted TCP packets to the NVMe over TCP driver.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 7 Feb 2024
- **Updated:** 6 Nov 2025
- **Also known as:** DEBIAN-CVE-2023-6356, GHSA-98fx-x879-qp6f, UBUNTU-CVE-2023-6356

## What is CVE-2023-6356?

CVE-2023-6356 is a medium-severity vulnerability in Debian Debian Linux, published on 7 Feb 2024. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A flaw was found in the Linux kernel's NVMe driver. This issue may allow an unauthenticated malicious actor to send a set of crafted TCP packages when using NVMe over TCP, leading the NVMe driver to a NULL pointer dereference in the NVMe driver and causing kernel panic and a denial of service.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2023-6356?

It affects 17 products.


Products: Debian Debian Linux, Linux kernel, Redhat Codeready Linux Builder Eus, Redhat Codeready Linux Builder Eus for Power Little Endian Eus, Redhat Codeready Linux Builder for Arm64 Eus, Redhat Codeready Linux Builder for Ibm Z Systems Eus, Redhat Enterprise Linux, Redhat Enterprise Linux Eus, Redhat Enterprise Linux for Arm 64 Eus, Redhat Enterprise Linux for Ibm Z Systems Eus, Redhat Enterprise Linux for Power Little Endian Eus, Redhat Enterprise Linux for Real Time, Redhat Enterprise Linux for Real Time for Nfv, Redhat Enterprise Linux Server Aus, Redhat Enterprise Linux Server for Power Little Endian Update Services for Sap Solutions, Redhat Enterprise Linux Server Tus, Redhat Virtualization Host.

## How do I fix CVE-2023-6356?

Apply the vendor's patch.

## Is CVE-2023-6356 being exploited?

There is no known exploitation of CVE-2023-6356 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-6356 and fix it if it is affected.

What it is: CVE-2023-6356 is a medium-severity vulnerability in Debian Debian Linux, published on 7 Feb 2024. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-6356 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2023-6356/ (Markdown: https://insights.sbomify.com/CVE-2023-6356/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-6356
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-6356
- OSV: https://osv.dev/vulnerability/CVE-2023-6356

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-6356/
Summaries are generated and may contain mistakes; the official description above is the record.