CVE-2023-6683Network attack vector

Authenticated process crash via uninitialized clipboard callback

Published Jan 12, 2024 · Updated Feb 25, 2026

Denial of service in the QEMU VNC server in Red Hat Enterprise Linux 8 and 9 allows remote authenticated users to crash QEMU. A ClientCutText request can reach qemu_clipboard_request() before capability negotiation initializes info->owner->request, causing a call through a NULL callback. Successful VNC authentication and access to a virtual machine's VNC endpoint are required; exploitation terminates the affected QEMU process and interrupts that guest.

CVSS severity6.5
Medium
EPSS probability1.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the QEMU VNC server in Red Hat Enterprise Linux 8 and 9 allows remote authenticated users to crash QEMU. A ClientCutText request can reach qemu_clipboard_request() before capability negotiation initializes info->owner->request, causing a call through a NULL callback. Successful VNC authentication and access to a virtual machine's VNC endpoint are required; exploitation terminates the affected QEMU process and interrupts that guest.

The record

CVE
CVE-2023-6683
Published
Jan 12, 2024
Updated
Feb 25, 2026
Vendor
Red Hat
Product
Red Hat Enterprise Linux 8
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 12, 2024CVE publishedPublication date reported by the CVE source.
  2. Feb 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Red Hat · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.

Published CVSS scores

6.5Red HatCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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