# CVE-2023-6693: Qemu: virtio-net: stack buffer overflow in virtio_net_flush_tx()

> A stack buffer overflow in QEMU's virtio-net device allows guest users to leak memory or potentially execute code when specific features are enabled.

- **Severity:** Medium 4.9 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 2 Jan 2024
- **Updated:** 25 Feb 2026
- **Also known as:** AZL-35675, AZL-35676, BELL-CVE-2023-6693, CLSA-2026-1779097389, DEBIAN-CVE-2023-6693, GHSA-835p-c6x8-xh5f, UBUNTU-CVE-2023-6693, openSUSE-SU-2024:13705-1

## What is CVE-2023-6693?

CVE-2023-6693 is a medium-severity memory corruption vulnerability in Fedoraproject Fedora, published on 2 Jan 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A stack based buffer overflow was found in the virtio-net device of QEMU. This issue occurs when flushing TX in the virtio_net_flush_tx function if guest features VIRTIO_NET_F_HASH_REPORT, VIRTIO_F_VERSION_1 and VIRTIO_NET_F_MRG_RXBUF are enabled. This could allow a malicious user to overwrite local variables allocated on the stack. Specifically, the `out_sg` variable could be used to read a part of process memory and send it to the wire, causing an information leak.

Weakness: CWE-787 (Out-of-bounds Write), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2023-6693?

It affects 3 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `qemu` | openSUSE:Tumbleweed | All versions | 8.2.1-1.1 |

Products: Fedoraproject Fedora, Qemu Qemu, Redhat Enterprise Linux.

## How do I fix CVE-2023-6693?

Apply the vendor's patch.

## Is CVE-2023-6693 being exploited?

There is no known exploitation of CVE-2023-6693 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-6693 and fix it if it is affected.

What it is: CVE-2023-6693 is a medium-severity memory corruption vulnerability in Fedoraproject Fedora, published on 2 Jan 2024. 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-2023-6693 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2023-6693/ (Markdown: https://insights.sbomify.com/CVE-2023-6693/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-6693
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-6693
- OSV: https://osv.dev/vulnerability/CVE-2023-6693

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-6693/
Summaries are generated and may contain mistakes; the official description above is the record.