---
id: CVE-2023-6683
title: 'Qemu: vnc: null pointer dereference in qemu_clipboard_request()'
summary: >-
  A flaw was found in the QEMU built-in VNC server while processing
  ClientCutText messages. The qemu_clipboard_request() function can be reached
  before vnc_server_cut_text_caps() was called and had the chance to initialize
  the clipboard pe…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
cvssSource: cna
cwe:
  - CWE-476
vendor: Red Hat
product: 'virt-devel:rhel'
affected:
  - 'virt-devel:rhel (all versions)'
  - 'virt:rhel (all versions)'
  - qemu-kvm (all versions)
  - qemu-kvm
  - qemu-kvm
  - qemu-kvm-ma
  - 'virt:av/qemu-kvm'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2024-07-13T20:19:24.320866Z'
published: '2024-01-12'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T11:37:28.638Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2023-6683'
references:
  - url: 'https://access.redhat.com/errata/RHSA-2024:2135'
    label: 'RHSA-2024:2135'
  - url: 'https://access.redhat.com/errata/RHSA-2024:2962'
    label: 'RHSA-2024:2962'
  - url: 'https://access.redhat.com/security/cve/CVE-2023-6683'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2254825'
    label: RHBZ#2254825
tags:
  - cve.org
epss: 0.01261
epssPercentile: 0.69703
ingestedAt: '2026-11-05T21:36:00.810Z'
---

## Overview

A flaw was found in the QEMU built-in VNC server while processing ClientCutText messages. The qemu_clipboard_request() function can be reached before vnc_server_cut_text_caps() was called and had the chance to initialize the clipboard peer, leading to a NULL pointer dereference. This could allow a malicious authenticated VNC client to crash QEMU and trigger a denial of service.

## Affected

- `virt-devel:rhel (all versions)`
- `virt:rhel (all versions)`
- `qemu-kvm (all versions)`
- `qemu-kvm`
- `qemu-kvm`
- `qemu-kvm-ma`
- `virt:av/qemu-kvm`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

### Workarounds

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.