Use-after-free in X.org Server and Xwayland - CVE-2026-34001

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Main Vulnerability Database Vulnerabilities #VU125989

Use-after-free in X.org Server and Xwayland - CVE-2026-34001

Published: April 14, 2026


Vulnerability identifier: #VU125989
CSH Severity: Low
CVSS v4: 6.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-34001
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to a use-after-free in miSyncTriggerFence() when walking the list of fences to trigger. A local user can trigger fence processing to cause a denial of service.

The issue occurs because freeing the await resource removes subsequent trigger entries from the list during iteration.


Affected software

X.org Server
IBM Power Hardware Management Console (HMC)
Xwayland
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 12 SP5 LTSS Extended
SUSE Linux Enterprise Server 12 SP5
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Server for SAP Applications 12
SUSE Linux Enterprise Server 12
SUSE Linux Enterprise High Performance Computing 12
SUSE Linux Enterprise Real Time 15
SUSE Linux Enterprise Desktop 15
SUSE Linux Enterprise Workstation Extension 15
OpenBSD
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Red Hat CodeReady Linux Builder for x86_64
Red Hat Enterprise Linux for IBM z Systems
Red Hat CodeReady Linux Builder for Power, little endian
Red Hat CodeReady Linux Builder for ARM 64
Red Hat CodeReady Linux Builder for IBM z Systems
Anolis OS
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux Server - AUS
Red Hat Enterprise Linux Server - TUS
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Development Tools Module
Basesystem Module
openSUSE Leap
openEuler
Fedora
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
tigervnc-server-module
tigervnc-server-minimal
tigervnc-server
tigervnc-icons
tigervnc-license
tigervnc
tigervnc-selinux
tigervnc-doc
xorg-x11-server-extra-debuginfo
xorg-x11-server-debugsource
xorg-x11-server
xorg-x11-server-debuginfo
xorg-x11-server-extra
xorg-x11-server-sdk
xorg-x11-server-source
xorg-x11-server (Red Hat package)
xorg-x11-server-Xephyr
xorg-x11-server-devel
xorg-x11-server-common
xorg-x11-server-Xvfb
xorg-x11-server-Xnest
xorg-x11-server-Xdmx
xorg-x11-server-Xorg
xorg-x11-server-doc
xorg-x11-server-help
xorg-x11-server-Xwayland (Red Hat package)
xorg-x11-server-Xvfb-debuginfo
xorg-x11-server-Xwayland-doc
xorg-x11-server-Xwayland-devel
xorg-x11-server-Xwayland
xwayland-devel
xwayland-debugsource
xwayland
xwayland-debuginfo

How to mitigate CVE-2026-34001

Install security update from vendor's website.

X.org Server - update to 21.1.22
Xwayland - update to 24.1.10
IBM Power Hardware Management Console (HMC) - addressed in versions 10.3.1064.1, 11.1.1112.1
tigervnc-server-module - update to 1.13.1-10
tigervnc-server-minimal - update to 1.13.1-10
tigervnc-server - update to 1.13.1-10
tigervnc-icons - update to 1.13.1-10
tigervnc-license - update to 1.13.1-10
tigervnc - update to 1.13.1-10
tigervnc-selinux - update to 1.13.1-10
tigervnc-doc - update to 1.13.1-10
tigervnc - addressed in versions 1.16.2-2.fc42, 1.16.2-2.fc43
xorg-x11-server-extra-debuginfo - addressed in versions 1.19.6-10.99.1, 1.20.3-150400.38.68.1, 21.1.4-150500.7.46.1, 21.1.11-150600.5.25.1, 21.1.15-150700.5.16.1
xorg-x11-server-debugsource - addressed in versions 1.19.6-10.99.1, 1.20.3-150400.38.68.1, 21.1.4-150500.7.46.1, 21.1.11-150600.5.25.1, 21.1.15-150700.5.16.1
xorg-x11-server - addressed in versions 1.19.6-10.99.1, 1.20.3-150400.38.68.1, 21.1.4-150500.7.46.1, 21.1.11-150600.5.25.1, 21.1.15-150700.5.16.1
xorg-x11-server-debuginfo - addressed in versions 1.19.6-10.99.1, 1.20.3-150400.38.68.1, 21.1.4-150500.7.46.1, 21.1.11-150600.5.25.1, 21.1.15-150700.5.16.1
xorg-x11-server-extra - addressed in versions 1.19.6-10.99.1, 1.20.3-150400.38.68.1, 21.1.4-150500.7.46.1, 21.1.11-150600.5.25.1, 21.1.15-150700.5.16.1
xorg-x11-server-sdk - addressed in versions 1.20.3-150400.38.68.1, 21.1.4-150500.7.46.1, 21.1.11-150600.5.25.1, 21.1.15-150700.5.16.1
xorg-x11-server-source - addressed in versions 1.20.3-150400.38.68.1, 21.1.4-150500.7.46.1, 21.1.11-150600.5.25.1
xorg-x11-server (Red Hat package) - addressed in versions 1.20.4-34.el7_9, 1.20.10-4.el8_4, 1.20.11-7.el8_6, 1.20.11-13.el9_0, 1.20.11-18.el8_8, 1.20.11-28.el8_10, 1.20.11-28.el9_4, 1.20.11-33.el9_7, 1.20.11-34.el9_8
xorg-x11-server-Xephyr - addressed in versions 1.20.11-28.0.1, 1.20.14-21
xorg-x11-server-source - addressed in versions 1.20.11-28.0.1, 1.20.14-21
xorg-x11-server-devel - addressed in versions 1.20.11-28.0.1, 1.20.14-21
xorg-x11-server-common - addressed in versions 1.20.11-28.0.1, 1.20.14-21
xorg-x11-server-Xvfb - addressed in versions 1.20.11-28.0.1, 1.20.14-21
xorg-x11-server-Xnest - addressed in versions 1.20.11-28.0.1, 1.20.14-21
xorg-x11-server-Xdmx - addressed in versions 1.20.11-28.0.1, 1.20.14-21
xorg-x11-server-Xorg - addressed in versions 1.20.11-28.0.1, 1.20.14-21
xorg-x11-server-doc - update to 1.20.11-28.0.1
xorg-x11-server-Xvfb - update to 1.20.11-44
xorg-x11-server - update to 1.20.11-44
xorg-x11-server-Xdmx - update to 1.20.11-44
xorg-x11-server-Xephyr - update to 1.20.11-44
xorg-x11-server-Xnest - update to 1.20.11-44
xorg-x11-server-common - update to 1.20.11-44
xorg-x11-server-debuginfo - update to 1.20.11-44
xorg-x11-server-debugsource - update to 1.20.11-44
xorg-x11-server-devel - update to 1.20.11-44
xorg-x11-server-help - update to 1.20.11-44
xorg-x11-server-source - update to 1.20.11-44
xorg-x11-server-Xwayland (Red Hat package) - addressed in versions 21.1.3-2.el8_6.6, 21.1.3-13.el8_8, 21.1.3-20.el8_10, 23.2.7-6.el9_7, 24.1.5-6.el10_1
xorg-x11-server-Xvfb - addressed in versions 21.1.4-150500.7.46.1, 21.1.11-150600.5.25.1, 21.1.15-150700.5.16.1
xorg-x11-server-Xvfb-debuginfo - addressed in versions 21.1.4-150500.7.46.1, 21.1.11-150600.5.25.1, 21.1.15-150700.5.16.1
xorg-x11-server - addressed in versions 21.1.22-1.fc42, 21.1.22-1.fc43, 21.1.22-1.fc44
xorg-x11-server-Xwayland-doc - update to 23.2.5-8
xorg-x11-server-Xwayland-devel - update to 23.2.5-8
xorg-x11-server-Xwayland - addressed in versions 23.2.5-8, 23.2.7-6
xwayland-devel - update to 24.1.1-150600.5.23.1
xwayland-debugsource - addressed in versions 24.1.1-150600.5.23.1, 24.1.5-150700.3.14.1
xwayland - addressed in versions 24.1.1-150600.5.23.1, 24.1.5-150700.3.14.1
xwayland-debuginfo - addressed in versions 24.1.1-150600.5.23.1, 24.1.5-150700.3.14.1
xorg-x11-server-Xwayland - addressed in versions 24.1.10-1.fc42, 24.1.10-1.fc43, 24.1.10-1.fc44, 24.1.11-1.fc42

External References

Related Security Bulletins