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NVD / CVE Program· CNA redhat

CVE-2023-6816: Xorg-x11-server: heap buffer overflow in devicefocusevent and procxiquerypointer

Noroxi assessment

Priority: Plan (action score 40/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 2.1% (FIRST EPSS); higher than 81.6% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: tigervnc (AlmaLinux:8) 1.13.1-2.el8_9.7.alma.1; tigervnc-icons (AlmaLinux:8) 1.13.1-2.el8_9.7.alma.1; tigervnc-license (AlmaLinux:8) 1.13.1-2.el8_9.7.alma.1.

Add it to your regular patch cycle. Upgrade to tigervnc (AlmaLinux:8) 1.13.1-2.el8_9.7.alma.1; tigervnc-icons (AlmaLinux:8) 1.13.1-2.el8_9.7.alma.1; tigervnc-license (AlmaLinux:8) 1.13.1-2.el8_9.7.alma.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A flaw was found in X.Org server. Both DeviceFocusEvent and the XIQueryPointer reply contain a bit for each logical button currently down. Buttons can be arbitrarily mapped to any value up to 255, but the X.Org Server was only allocating space for the device's particular number of buttons, leading to a heap overflow if a bigger value was used.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Jan 18, 2024
Updated
Jun 17, 2026
EPSS
2.1% · 81th percentile

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
9.8
CNA · redhat
9.8
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2023-6816

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
x.orgx server
x.orgxwayland
fedoraprojectfedora
redhatenterprise linux desktop
redhatenterprise linux server
redhatenterprise linux workstation
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux10.0
  • fedoraproject fedora39
  • redhat enterprise linux desktop7.0
  • redhat enterprise linux server7.0
  • redhat enterprise linux workstation7.0
  • x.org x serverbefore 21.1.11
  • x.org xwaylandbefore 23.2.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

  • Red Hat Red Hat Enterprise Linux 6

    • all versionsunknown

  • Red Hat Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION

    • 0:1.1.0-25.el6_10.13 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 7

    • 0:1.20.4-27.el7_9 and laternot affected · rpm
    • 0:1.8.0-31.el7_9 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8

    • 0:1.13.1-2.el8_9.7 and laternot affected · rpm
    • 0:1.20.11-22.el8 and laternot affected · rpm
    • 0:21.1.3-15.el8 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.2 Advanced Update Support

    • 0:1.9.0-15.el8_2.9 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.2 Telecommunications Update Service

    • 0:1.9.0-15.el8_2.9 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.2 Update Services for SAP Solutions

    • 0:1.9.0-15.el8_2.9 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support

    • 0:1.11.0-8.el8_4.8 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.4 Telecommunications Update Service

    • 0:1.11.0-8.el8_4.8 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions

    • 0:1.11.0-8.el8_4.8 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support

    • 0:1.12.0-6.el8_6.9 and laternot affected · rpm

  • Red Hat Red Hat Enterprise Linux 8.8 Extended Update Support

    • 0:1.12.0-15.el8_8.7 and laternot affected · rpm

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:8tigervncbefore 1.13.1-2.el8_9.7.alma.11.13.1-2.el8_9.7.alma.1
AlmaLinux:8tigervnc-iconsbefore 1.13.1-2.el8_9.7.alma.11.13.1-2.el8_9.7.alma.1
AlmaLinux:8tigervnc-licensebefore 1.13.1-2.el8_9.7.alma.11.13.1-2.el8_9.7.alma.1
AlmaLinux:8tigervnc-selinuxbefore 1.13.1-2.el8_9.7.alma.11.13.1-2.el8_9.7.alma.1
AlmaLinux:8tigervnc-serverbefore 1.13.1-2.el8_9.7.alma.11.13.1-2.el8_9.7.alma.1
AlmaLinux:8tigervnc-server-minimalbefore 1.13.1-2.el8_9.7.alma.11.13.1-2.el8_9.7.alma.1
AlmaLinux:8tigervnc-server-modulebefore 1.13.1-2.el8_9.7.alma.11.13.1-2.el8_9.7.alma.1
AlmaLinux:8xorg-x11-server-Xwaylandbefore 21.1.3-15.el821.1.3-15.el8
AlmaLinux:9tigervncbefore 1.13.1-3.el9_3.6.alma.11.13.1-3.el9_3.6.alma.1
AlmaLinux:9tigervnc-iconsbefore 1.13.1-3.el9_3.6.alma.11.13.1-3.el9_3.6.alma.1
AlmaLinux:9tigervnc-licensebefore 1.13.1-3.el9_3.6.alma.11.13.1-3.el9_3.6.alma.1
AlmaLinux:9tigervnc-selinuxbefore 1.13.1-3.el9_3.6.alma.11.13.1-3.el9_3.6.alma.1
AlmaLinux:9tigervnc-serverbefore 1.13.1-3.el9_3.6.alma.11.13.1-3.el9_3.6.alma.1
AlmaLinux:9tigervnc-server-minimalbefore 1.13.1-3.el9_3.6.alma.11.13.1-3.el9_3.6.alma.1
AlmaLinux:9tigervnc-server-modulebefore 1.13.1-3.el9_3.6.alma.11.13.1-3.el9_3.6.alma.1
AlmaLinux:9xorg-x11-server-commonbefore 1.20.11-24.el91.20.11-24.el9
AlmaLinux:9xorg-x11-server-develbefore 1.20.11-24.el91.20.11-24.el9
AlmaLinux:9xorg-x11-server-sourcebefore 1.20.11-24.el91.20.11-24.el9
AlmaLinux:9xorg-x11-server-Xdmxbefore 1.20.11-24.el91.20.11-24.el9
AlmaLinux:9xorg-x11-server-Xephyrbefore 1.20.11-24.el91.20.11-24.el9
AlmaLinux:9xorg-x11-server-Xnestbefore 1.20.11-24.el91.20.11-24.el9
AlmaLinux:9xorg-x11-server-Xorgbefore 1.20.11-24.el91.20.11-24.el9
AlmaLinux:9xorg-x11-server-Xvfbbefore 1.20.11-24.el91.20.11-24.el9
AlmaLinux:9xorg-x11-server-Xwaylandbefore 22.1.9-5.el922.1.9-5.el9

+96

Same product

x.org: all records

Other highest-scoring records for the same primary product.

  • CVE-2018-14665A flaw was found in xorg-x11-server before 1.20.3.
    40Plan
  • CVE-2007-6427The XInput extension in X.Org Xserver before 1.4.1 allows context-dependent attackers to execute arbitrary code via requests related to byte
    38Monitor
  • CVE-2026-56000xorg-x11-server / xwayland GLX contextTags Use-After-Free in CommonMakeCurrent()
    36Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2023-5574Oct 25, 2023 · Xorg-x11-server: use-after-free bug in damagedestroy
    28Monitor
  • ← EarlierCVE-2023-6478Dec 13, 2023 · Xorg-x11-server: out-of-bounds memory read in rrchangeoutputproperty and rrchangeproviderproperty
    30Monitor
  • Later →CVE-2024-0408Jan 18, 2024 · Xorg-x11-server: selinux unlabeled glx pbuffer
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
almalinux:tigervnc1.13.1-3.el9_3.6.alma.1 · AlmaLinux:9Package registry (OSV)
almalinux:tigervnc-icons1.13.1-3.el9_3.6.alma.1 · AlmaLinux:9Package registry (OSV)
almalinux:tigervnc-license1.13.1-3.el9_3.6.alma.1 · AlmaLinux:9Package registry (OSV)
almalinux:tigervnc-selinux1.13.1-3.el9_3.6.alma.1 · AlmaLinux:9Package registry (OSV)
almalinux:tigervnc-server1.13.1-3.el9_3.6.alma.1 · AlmaLinux:9Package registry (OSV)
almalinux:tigervnc-server-minimal1.13.1-3.el9_3.6.alma.1 · AlmaLinux:9Package registry (OSV)
almalinux:tigervnc-server-module1.13.1-3.el9_3.6.alma.1 · AlmaLinux:9Package registry (OSV)
almalinux:xorg-x11-server-Xdmx1.20.11-24.el9 · AlmaLinux:9Package registry (OSV)
almalinux:xorg-x11-server-Xephyr1.20.11-24.el9 · AlmaLinux:9Package registry (OSV)
almalinux:xorg-x11-server-Xnest1.20.11-24.el9 · AlmaLinux:9Package registry (OSV)
almalinux:xorg-x11-server-Xorg1.20.11-24.el9 · AlmaLinux:9Package registry (OSV)
almalinux:xorg-x11-server-Xvfb1.20.11-24.el9 · AlmaLinux:9Package registry (OSV)
debian:xorg-server2:21.1.7-3+deb12u5 · Debian:12Package registry (OSV)
debian:xwayland2:23.2.4-1 · Debian:13Package registry (OSV)
opensuse:xorg-x11-server21.1.4-150500.7.18.1 · openSUSE:Leap 15.5Package registry (OSV)
opensuse:xwayland22.1.5-150500.7.14.1 · openSUSE:Leap 15.5Package registry (OSV)
red hat:tigervnc0:1.13.1-3.el9_3.6 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:xorg-x11-server0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-common0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-debuginfo0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-devel0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-source0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-Xdmx0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-Xephyr0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-Xnest0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-Xorg0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-Xvfb0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:xorg-x11-server-Xwayland0:1.20.4-27.el7_9 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
rocky linux:tigervnc0:1.13.1-2.el8_9.7 · Rocky Linux:8Package registry (OSV)
suse:xorg-x11-server21.1.4-150500.7.18.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP5Package registry (OSV)

+1

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2022-46340400 days apartA vulnerability was found in X.Org.
    36Monitor
  • CVE-2022-46341400 days apartA vulnerability was found in X.Org.
    36Monitor
  • CVE-2024-04090 days apartXorg-x11-server: selinux context corruption
    31Monitor
  • CVE-2024-022922 days apartXorg-x11-server: reattaching to different master device may lead to out-of-bounds memory access
    31Monitor
  • CVE-2023-536785 days apartXorg-x11-server: out-of-bounds write in xichangedeviceproperty/rrchangeoutputproperty
    31Monitor
  • CVE-2025-26598404 days apartXorg: xwayland: out-of-bounds write in createpointerbarrierclient()
    31Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (19 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records