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Fencer Vulns
medium 6.5

CVE-2023-6683 json

Qemu: vnc: null pointer dereference in qemu_clipboard_request()

published 2024-01-12 2 y ago modified 2026-11-05 3 d ago also EUVD-2023-58904

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 69%
public exploits
0
none known

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 peer, leading to a NULL pointer dereference. This could allow a malicious authenticated VNC client to crash QEMU and trigger a denial of service.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 8 8100020240314161907.e155f54d
  • Red Hat Red Hat Enterprise Linux 9 17:8.2.0-11.el9_4
  • qemu Debian 12 1:7.2+dfsg-7+deb12u4
  • qemu Debian 14, Debian 13 1:8.2.0+ds-5

debian advisories DEBIAN-CVE-2023-6683

  • qemu Ubuntu 22.04 LTS 1:6.2+dfsg-2ubuntu6.22

ubuntu advisories UBUNTU-CVE-2023-6683

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • SLOF RHEL 8 20210217-2.module+el8.10.0+20141+6faa2812
  • hivex RHEL 8 1.3.18-23.module+el8.9.0+18724+20190c23
  • netcf RHEL 8 0.2.8-12.module+el8.9.0+18724+20190c23
  • swtpm RHEL 8 0.7.0-4.20211109gitb79fd91.module+el8.9.0+18724+20190c23
  • libnbd RHEL 8 1.6.0-5.module+el8.9.0+18724+20190c23
  • nbdkit RHEL 8 1.24.0-5.module+el8.9.0+18724+20190c23
  • libtpms RHEL 8 0.9.1-2.20211126git1ff6fe1f43.module+el8.9.0+18724+20190c23
  • libvirt RHEL 8 8.0.0-23.module+el8.10.0+21023+5962ee04

red hat advisories RHSA-2024:2962RHSA-2024:2135

  • qemu SLE Module for Server Applications 15 SP5, SLE Module for Package Hub 15 SP5, SLE Module for Basesystem 15 SP5 +2 more 7.1.0-150500.49.15.1
  • qemu SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE Micro 5.4 +7 more 6.2.0-150400.37.29.1

suse advisories SUSE-SU-2024:1438-2SUSE-SU-2024:1438-1SUSE-SU-2024:1394-1

  • qemu-kvm AlmaLinux 9 17:8.2.0-11.el9_4
  • qemu-img AlmaLinux 9 17:8.2.0-11.el9_4
  • qemu-kvm-core AlmaLinux 9 17:8.2.0-11.el9_4
  • qemu-kvm-tools AlmaLinux 9 17:8.2.0-11.el9_4
  • qemu-pr-helper AlmaLinux 9 17:8.2.0-11.el9_4
  • qemu-kvm-common AlmaLinux 9 17:8.2.0-11.el9_4
  • qemu-guest-agent AlmaLinux 9 17:8.2.0-11.el9_4
  • qemu-kvm-audio-pa AlmaLinux 9 17:8.2.0-11.el9_4

almalinux advisories ALSA-2024:2135

  • hivex Rocky Linux 8 1.3.18-23.module+el8.10.0+1590+a67ab969
  • netcf Rocky Linux 8 0.2.8-12.module+el8.10.0+1590+a67ab969
  • swtpm Rocky Linux 8 0.7.0-4.20211109gitb79fd91.module+el8.10.0+1590+a67ab969
  • libnbd Rocky Linux 8 1.6.0-5.module+el8.10.0+1590+a67ab969
  • nbdkit Rocky Linux 8 1.24.0-5.module+el8.10.0+1590+a67ab969
  • libtpms Rocky Linux 8 0.9.1-2.20211126git1ff6fe1f43.module+el8.10.0+1590+a67ab969
  • libvirt Rocky Linux 8 8.0.0-23.1.module+el8.10.0+1779+84732956
  • seabios Rocky Linux 8 1.16.0-4.module+el8.9.0+1408+7b966129

rocky linux advisories RLSA-2024:2962RLSA-2024:2135

  • qemu CBL-Mariner 2.0 6.2.0-21
  • qemu Azure Linux 3.0 8.2.0-13

azure linux advisories AZL-40048AZL-43054

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-6683 updated cvss 6.5

QEMU: VNC: NULL pointer dereference in qemu_clipboard_request()

  • Red Hat Enterprise Linux AppStream (v. 8) libnbd 1.6.0-5.module+el8.9.0+18724+20190c23, netcf 0.2.8-12.module+el8.9.0+18724+20190c23, hivex 1.3.18-23.module+el8.9.0+18724+20190c23, nbdfuse 1.6.0-5.module+el8.9.0+18724+20190c23, nbdkit 1.24.0-5.module+el8.9.0+18724+20190c23, seabios 1.16.0-4.module+el8.9.0+19570+14a90618, +104 more
    fixed: vendor fix RHSA-2024:2962
  • Red Hat Enterprise Linux AppStream (v. 9) qemu-img 8.2.0-11.el9_4, qemu-kvm 8.2.0-11.el9_4, qemu-kvm-core 8.2.0-11.el9_4, qemu-kvm-tools 8.2.0-11.el9_4, qemu-pr-helper 8.2.0-11.el9_4, qemu-kvm-common 8.2.0-11.el9_4, +13 more
    fixed: vendor fix RHSA-2024:2135
  • Red Hat Enterprise Linux CRB (v. 8) libnbd 1.6.0-5.module+el8.9.0+18724+20190c23, netcf 0.2.8-12.module+el8.9.0+18724+20190c23, hivex 1.3.18-23.module+el8.9.0+18724+20190c23, nbdfuse 1.6.0-5.module+el8.9.0+18724+20190c23, seabios 1.16.0-4.module+el8.9.0+19570+14a90618, SLOF 20210217-2.module+el8.10.0+20141+6faa2812, +38 more
    fixed: vendor fix RHSA-2024:2962
  • Red Hat Enterprise Linux 6 qemu-img, qemu-kvm, qemu-kvm-tools, qemu-guest-agent, qemu-guest-agent-win32 Red Hat Enterprise Linux 7 qemu-img, qemu-kvm, libcacard, qemu-img-ma, qemu-kvm-ma, qemu-kvm-tools, +5 more Red Hat Enterprise Linux 8 Advanced Virtualization qemu-img, qemu-kvm, qemu-kiwi, qemu-kvm-core, qemu-kvm-tests, qemu-kvm-common, +9 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

1.26% chance of exploitation in the next 30 days, higher than 69% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8 Advanced Virtualization

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.