# CVE-2023-6683: Qemu: vnc: null pointer dereference in qemu_clipboard_request()

Status: published. Published: 2024-01-12. Updated: 2026-11-05.

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.

## Remediation

- workaround: 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. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 8 (virt-devel:rhel): ≥ 8100020240314161907.e155f54d; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (virt:rhel): ≥ 8100020240314161907.e155f54d; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (qemu-kvm): ≥ 17:8.2.0-11.el9_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (qemu-kvm): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (qemu-kvm): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (qemu-kvm-ma): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 Advanced Virtualization (virt:av/qemu-kvm): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 6.5 (medium); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 1.26% as of 2026-11-04; percentile 69.70%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-476

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2024:2135 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:2962 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2023-6683 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2254825 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2024:2135 (ADP: CVE; vendor-advisory, x_refsource_REDHAT, x_transferred)

- https://access.redhat.com/errata/RHSA-2024:2962 (ADP: CVE; vendor-advisory, x_refsource_REDHAT, x_transferred)

- https://access.redhat.com/security/cve/CVE-2023-6683 (ADP: CVE; vdb-entry, x_refsource_REDHAT, x_transferred)

- https://bugzilla.redhat.com/show_bug.cgi?id=2254825 (ADP: CVE; issue-tracking, x_refsource_REDHAT, x_transferred)

- https://security.netapp.com/advisory/ntap-20240223-0001/ (ADP: CVE; x_transferred)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2023-6683; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2023-6683; retrieved 2026-11-05; source updated Not reported

Revision: e549d31942d7034cacc81fe3ebade0f02260e533929373e82fe6b3e8fb3a959b

Canonical: https://y2.dev/cve/CVE-2023-6683

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