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

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.

Published: 2024-01-18 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2023-6816 is rated High Risk (66/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 2.11%). Mandatory action: High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-6816

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 3.02% 2.11% -0.91%
2 2026-04-19 3.26% 3.02% -0.25%
3 2026-02-05 3.26%

Full EPSS history (32 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-6816

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 5.9 [email protected]
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
3.9 5.9 [email protected]

Weakness enumeration for CVE-2023-6816

OS Trackers for CVE-2023-6816

vendor priority summary link
alpine CVE-2023-6816: 2 source package rows (xorg-server, xwayland); 44 state rows across 5 repos (3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 16, open 28. https://security.alpinelinux.org/vuln/CVE-2023-6816
debian not yet assigned CVE-2023-6816 not yet assigned priority: Debian including 2 source packages (xorg-server, xwayland), 9 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 8, open 1. https://security-tracker.debian.org/tracker/CVE-2023-6816
gentoo normal CVE-2023-6816: 1 GLSA(s) (202401-30), 2 atom(s) (x11-base/xorg-server, x11-base/xwayland); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-6816
redhat high https://access.redhat.com/security/cve/CVE-2023-6816
suse high https://www.suse.com/security/cve/CVE-2023-6816/
ubuntu medium CVE-2023-6816 medium priority: Ubuntu including 11 source packages (xorg, xorg-hwe-16.04, …), 132 status rows across 12 suites (bionic, focal, jammy, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 84, released 19, not-affected 14, needs-triage 10, ignored 5. https://ubuntu.com/security/CVE-2023-6816

Affected software / configurations for CVE-2023-6816

Vendor Product Version Raw CPE
x.org x_server < 21.1.11 cpe:2.3:a:x.org:x_server:*:*:*:*:*:*:*:*
x.org xwayland < 23.2.4 cpe:2.3:a:x.org:xwayland:*:*:*:*:*:*:*:*
fedoraproject fedora 39 cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*
redhat enterprise_linux_desktop 7.0 cpe:2.3:o:redhat:enterprise_linux_desktop:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_server 7.0 cpe:2.3:o:redhat:enterprise_linux_server:7.0:*:*:*:*:*:*:*
redhat enterprise_linux_workstation 7.0 cpe:2.3:o:redhat:enterprise_linux_workstation:7.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2023-6816

URL Tags
https://access.redhat.com/errata/RHSA-2024:0320 Third Party Advisory
https://access.redhat.com/errata/RHSA-2024:0557
https://access.redhat.com/errata/RHSA-2024:0558
https://access.redhat.com/errata/RHSA-2024:0597
https://access.redhat.com/errata/RHSA-2024:0607
https://access.redhat.com/errata/RHSA-2024:0614
https://access.redhat.com/errata/RHSA-2024:0617
https://access.redhat.com/errata/RHSA-2024:0621
https://access.redhat.com/errata/RHSA-2024:0626
https://access.redhat.com/errata/RHSA-2024:0629
https://access.redhat.com/errata/RHSA-2024:2169
https://access.redhat.com/errata/RHSA-2024:2170
https://access.redhat.com/errata/RHSA-2024:2995
https://access.redhat.com/errata/RHSA-2024:2996
https://access.redhat.com/errata/RHSA-2025:12751
https://access.redhat.com/security/cve/CVE-2023-6816 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2257691 Issue Tracking
http://www.openwall.com/lists/oss-security/2024/01/18/1
https://lists.debian.org/debian-lts-announce/2024/01/msg00016.html
https://lists.fedoraproject.org/archives/list/[email protected]/message/5J4H7CH565ALSZZYKOJFYDA5KFLG6NUK/
https://lists.fedoraproject.org/archives/list/[email protected]/message/EJBMCWQ54R6ZL3MYU2D2JBW6JMZL7BQW/
https://lists.fedoraproject.org/archives/list/[email protected]/message/IZ75X54CN4IFYMIV7OK3JVZ57FHQIGIC/
https://security.gentoo.org/glsa/202401-30
https://security.netapp.com/advisory/ntap-20240307-0006/
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