CVE-2023-6816Network attack vector

Memory corruption via undersized button-state bitmap

Published Jan 18, 2024 · Updated Mar 19, 2026

Heap buffer overflow in X.Org Server before 21.1.11 and Xwayland before 23.2.4 allows remote attackers to corrupt server memory. DeviceFocusEvent and ProcXIQueryPointer size button-state bitmaps from the device button count even though logical mappings can reach 255. An unauthenticated client that can reach the X server can supply an oversized index, causing a crash or arbitrary code execution in the server process.

CVSS severity9.8
Critical
EPSS probability2.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in X.Org Server before 21.1.11 and Xwayland before 23.2.4 allows remote attackers to corrupt server memory. DeviceFocusEvent and ProcXIQueryPointer size button-state bitmaps from the device button count even though logical mappings can reach 255. An unauthenticated client that can reach the X server can supply an oversized index, causing a crash or arbitrary code execution in the server process.

The record

CVE
CVE-2023-6816
Published
Jan 18, 2024
Updated
Mar 19, 2026
Vendor
Red Hat
Product
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Classifications
CWE-787, T1210
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 18, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 privilegesunauthenticated

What is affected?

Red Hat · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.0 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 7Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.2 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.2 Advanced Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.2 Telecommunications Update ServiceAffected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 6 Extended Lifecycle Support - ExtensionAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.2 Update Services for SAP SolutionsAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.4 Telecommunications Update ServiceAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.8 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.6 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.4 Update Services for SAP SolutionsAffected versions are unavailable in this record.

Published CVSS scores

9.8Red Hat, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1210Exploitation of Remote Services

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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