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Fencer Vulns
high 7.8

CVE-2026-34001 json

Xorg: xwayland: x.org x server: use-after-free vulnerability leads to server crash and potential memory corruption

published 2026-04-23 6 mo ago modified 2026-11-04 4 d ago also EUVD-2026-25230

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 18%
public exploits
0
none known

Summary

A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic, specifically within the miSyncTriggerFence() function. An attacker with access to the X11 server can exploit this without user interaction, leading to a server crash and potentially enabling memory corruption. This could result in a denial of service or further compromise of the system.

Patch / fix

  • Red Hat Red Hat Enterprise Linux 10 0:24.1.5-6.el10_1, 0:24.1.9-4.el10_2
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support 0:24.1.5-6.el10_0
  • Red Hat Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION 0:1.1.0-25.el6_10.16
  • Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support 0:1.8.0-36.el7_9.4, 0:1.20.4-34.el7_9
  • Red Hat Red Hat Enterprise Linux 8 0:1.15.0-9.el8_10, 0:1.20.11-28.el8_10, 0:21.1.3-20.el8_10
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:1.11.0-8.el8_4.15, 0:1.20.10-4.el8_4
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:1.11.0-8.el8_4.15, 0:1.20.10-4.el8_4
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:1.12.0-6.el8_6.17, 0:1.20.11-7.el8_6, 0:21.1.3-2.el8_6.6
  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 0:1.12.0-6.el8_6.17
  • Red Hat Red Hat Enterprise Linux 8.6 Telecommunications Update Service 0:1.20.11-7.el8_6, 0:21.1.3-2.el8_6.6
  • Red Hat Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions 0:1.20.11-7.el8_6, 0:21.1.3-2.el8_6.6
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:1.12.0-15.el8_8.17, 0:1.20.11-18.el8_8, 0:21.1.3-13.el8_8
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:1.12.0-15.el8_8.17, 0:1.20.11-18.el8_8, 0:21.1.3-13.el8_8
  • Red Hat Red Hat Enterprise Linux 9 0:1.15.0-6.el9_7.1, 0:1.15.0-7.el9_8.1, 0:1.20.11-33.el9_7, 0:1.20.11-34.el9_8, 0:23.2.7-6.el9_7, 0:24.1.9-4.el9_8
  • Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions 0:1.11.0-22.el9_0.17, 0:1.20.11-13.el9_0, 0:21.1.3-5.el9_0
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:1.12.0-14.el9_2.14, 0:1.20.11-20.el9_2, 0:21.1.3-10.el9_2
  • Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support 0:1.13.1-8.el9_4.9, 0:1.20.11-28.el9_4, 0:22.1.9-8.el9_4
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:1.14.1-10.el9_6, 0:1.20.11-33.el9_6, 0:23.2.7-6.el9_6
  • xwayland Debian 14 2:24.1.10-1
  • xorg-server Debian 12 2:21.1.7-3+deb12u12
  • xorg-server Debian 13 2:21.1.16-1.3+deb13u2
  • xorg-server Debian 14 2:21.1.22-1

debian advisories DEBIAN-CVE-2026-34001

  • xorg-x11-server RHEL 9 1.20.11-34.el9_8
  • xorg-x11-server-Xdmx RHEL 9 1.20.11-34.el9_8
  • xorg-x11-server-Xorg RHEL 9 1.20.11-34.el9_8
  • xorg-x11-server-Xvfb RHEL 9 1.20.11-34.el9_8
  • xorg-x11-server-Xnest RHEL 9 1.20.11-34.el9_8
  • xorg-x11-server-common RHEL 9 1.20.11-34.el9_8
  • xorg-x11-server-source RHEL 9 1.20.11-34.el9_8
  • xorg-x11-server-Xephyr RHEL 9 1.20.11-34.el9_8

red hat advisories RHSA-2026:24341RHSA-2026:23496RHSA-2026:23254RHSA-2026:23255RHSA-2026:22456RHSA-2026:22424

  • xwayland SLES for SAP applications 16.0, SLES 16.0 24.1.6-160000.4.1
  • xorg-x11-server SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE High Performance Computing 15 SP5-LTSS +1 more 21.1.4-150500.7.46.1
  • xorg-x11-server SLES for SAP 15 SP4, SLES 15 SP4-LTSS, SLE High Performance Computing 15 SP4-LTSS +1 more 1.20.3-150400.38.68.1
  • xorg-x11-server SLES for SAP 15 SP6, SLES 15 SP6-LTSS, openSUSE Leap 15.6 21.1.11-150600.5.25.1
  • xorg-x11-server SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 21.1.15-150700.5.16.1
  • xwayland openSUSE Leap 15.6 24.1.1-150600.5.23.1
  • xwayland SLE Workstation Extension 15 SP7 24.1.5-150700.3.14.1
  • xorg-x11-server SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 1.19.6-10.99.1

suse advisories SUSE-SU-2026:21211-1SUSE-SU-2026:1335-1SUSE-SU-2026:1333-1SUSE-SU-2026:1332-1SUSE-SU-2026:1331-1SUSE-SU-2026:1330-1

  • xwayland openSUSE Leap 16.0 24.1.6-160000.4.1
  • xorg-x11-server openSUSE Leap 16.0 21.1.15-160000.4.1
  • xorg-x11-server openSUSE Tumbleweed 21.1.21-5.1
  • xwayland openSUSE Tumbleweed 24.1.9-2.1

opensuse advisories openSUSE-SU-2026:20560-1openSUSE-SU-2026:20544-1openSUSE-SU-2026:10556-1openSUSE-SU-2026:10557-1

  • xorg-x11-server-Xwayland AlmaLinux 10 24.1.9-4.el10_2
  • tigervnc AlmaLinux 9 1.15.0-7.el9_8.1
  • tigervnc-icons AlmaLinux 9 1.15.0-7.el9_8.1
  • tigervnc-server AlmaLinux 9 1.15.0-7.el9_8.1
  • tigervnc-license AlmaLinux 9 1.15.0-7.el9_8.1
  • tigervnc-selinux AlmaLinux 9 1.15.0-7.el9_8.1
  • tigervnc-server-module AlmaLinux 9 1.15.0-7.el9_8.1
  • tigervnc-server-minimal AlmaLinux 9 1.15.0-7.el9_8.1

almalinux advisories ALSA-2026:19125ALSA-2026:19342ALSA-2026:19343ALSA-2026:19344ALSA-2026:13414ALSA-2026:11656

  • xorg-x11-server-Xwayland Rocky Linux 10 24.1.9-4.el10_2
  • tigervnc Rocky Linux 9 1.15.0-7.el9_8.1
  • xorg-x11-server Rocky Linux 9 1.20.11-34.el9_8
  • xorg-x11-server-Xwayland Rocky Linux 9 24.1.9-4.el9_8
  • tigervnc Rocky Linux 8 1.15.0-9.el8_10
  • xorg-x11-server-Xwayland Rocky Linux 10 24.1.5-6.el10_1
  • xorg-x11-server-Xwayland Rocky Linux 8 21.1.3-20.el8_10
  • xorg-x11-server Rocky Linux 8 1.20.11-28.el8_10

rocky linux advisories RLSA-2026:19125RLSA-2026:19342RLSA-2026:19343RLSA-2026:19344RLSA-2026:13414RLSA-2026:11352

  • xwayland Alpine 3.24, Alpine 3.23 24.1.10-r0
  • xorg-server Alpine 3.24, Alpine 3.23 21.1.22-r0

alpine advisories ALPINE-CVE-2026-34001

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • xorg-x11-server-Xwayland Azure Linux 3.0 24.1.6-4

azure linux advisories AZL-84842

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-34001 updated cvss 7.8

xorg: xwayland: X.Org X server: Use-after-free vulnerability leads to server crash and potential memory corruption

  • Red Hat Enterprise Linux 6 xorg-x11-server, xorg-x11-server-Xdmx, xorg-x11-server-Xorg, xorg-x11-server-Xvfb, xorg-x11-server-Xnest, xorg-x11-server-common, +2 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder EUS (v.9.4) xorg-x11-server-source 1.20.11-28.el9_4
    fixed: vendor fix RHSA-2026:20555
  • Red Hat CodeReady Linux Builder EUS (v.9.6) xorg-x11-server-source 1.20.11-33.el9_6, xorg-x11-server-Xwayland 23.2.7-6.el9_6
    fixed: vendor fix RHSA-2026:20558
  • Red Hat Enterprise Linux AppStream (v. 8) tigervnc 1.15.0-9.el8_10, tigervnc-icons 1.15.0-9.el8_10, tigervnc-server 1.15.0-9.el8_10, tigervnc-license 1.15.0-9.el8_10, tigervnc-selinux 1.15.0-9.el8_10, xorg-x11-server 1.20.11-28.el8_10, +9 more
    fixed: vendor fix RHSA-2026:13414
  • Red Hat Enterprise Linux AppStream (v. 9) tigervnc 1.15.0-6.el9_7.1, tigervnc 1.15.0-7.el9_8.1, tigervnc-icons 1.15.0-6.el9_7.1, tigervnc-icons 1.15.0-7.el9_8.1, tigervnc-server 1.15.0-6.el9_7.1, tigervnc-server 1.15.0-7.el9_8.1, +24 more
    fixed: vendor fix RHSA-2026:10739
  • Red Hat Enterprise Linux AppStream (v. 10) xorg-x11-server-Xwayland 24.1.5-6.el10_1, xorg-x11-server-Xwayland 24.1.9-4.el10_2
    fixed: vendor fix RHSA-2026:11352
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) tigervnc 1.11.0-8.el8_4.15, xorg-x11-server 1.20.10-4.el8_4, tigervnc-icons 1.11.0-8.el8_4.15, tigervnc-server 1.11.0-8.el8_4.15, tigervnc-license 1.11.0-8.el8_4.15, tigervnc-selinux 1.11.0-8.el8_4.15, +9 more
    fixed: vendor fix RHSA-2026:23254
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) tigervnc 1.12.0-6.el8_6.17, xorg-x11-server 1.20.11-7.el8_6, tigervnc-icons 1.12.0-6.el8_6.17, tigervnc-server 1.12.0-6.el8_6.17, tigervnc-license 1.12.0-6.el8_6.17, tigervnc-selinux 1.12.0-6.el8_6.17, +9 more
    fixed: vendor fix RHSA-2026:24341
show 19 more
  • Red Hat Enterprise Linux AppStream E4S (v.8.6) xorg-x11-server 1.20.11-7.el8_6, xorg-x11-server-Xdmx 1.20.11-7.el8_6, xorg-x11-server-Xorg 1.20.11-7.el8_6, xorg-x11-server-Xvfb 1.20.11-7.el8_6, xorg-x11-server-Xnest 1.20.11-7.el8_6, xorg-x11-server-common 1.20.11-7.el8_6, +2 more
    fixed: vendor fix RHSA-2026:21718
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) tigervnc 1.12.0-15.el8_8.17, xorg-x11-server 1.20.11-18.el8_8, tigervnc-icons 1.12.0-15.el8_8.17, tigervnc-server 1.12.0-15.el8_8.17, tigervnc-license 1.12.0-15.el8_8.17, tigervnc-selinux 1.12.0-15.el8_8.17, +9 more
    fixed: vendor fix RHSA-2026:23255
  • Red Hat Enterprise Linux AppStream E4S (v.9.0) tigervnc 1.11.0-22.el9_0.17, xorg-x11-server 1.20.11-13.el9_0, tigervnc-icons 1.11.0-22.el9_0.17, tigervnc-server 1.11.0-22.el9_0.17, tigervnc-license 1.11.0-22.el9_0.17, tigervnc-selinux 1.11.0-22.el9_0.17, +9 more
    fixed: vendor fix RHSA-2026:21741
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) tigervnc 1.12.0-14.el9_2.14, xorg-x11-server 1.20.11-20.el9_2, tigervnc-icons 1.12.0-14.el9_2.14, tigervnc-server 1.12.0-14.el9_2.14, tigervnc-license 1.12.0-14.el9_2.14, tigervnc-selinux 1.12.0-14.el9_2.14, +9 more
    fixed: vendor fix RHSA-2026:20576
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) xorg-x11-server-Xwayland 24.1.5-6.el10_0
    fixed: vendor fix RHSA-2026:20563
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) tigervnc 1.13.1-8.el9_4.9, tigervnc-icons 1.13.1-8.el9_4.9, tigervnc-server 1.13.1-8.el9_4.9, xorg-x11-server 1.20.11-28.el9_4, tigervnc-license 1.13.1-8.el9_4.9, tigervnc-selinux 1.13.1-8.el9_4.9, +9 more
    fixed: vendor fix RHSA-2026:20575
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) tigervnc 1.14.1-10.el9_6, tigervnc-icons 1.14.1-10.el9_6, tigervnc-server 1.14.1-10.el9_6, tigervnc-license 1.14.1-10.el9_6, tigervnc-selinux 1.14.1-10.el9_6, xorg-x11-server 1.20.11-33.el9_6, +9 more
    fixed: vendor fix RHSA-2026:22424
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) tigervnc 1.11.0-8.el8_4.15, xorg-x11-server 1.20.10-4.el8_4, tigervnc-icons 1.11.0-8.el8_4.15, tigervnc-server 1.11.0-8.el8_4.15, tigervnc-license 1.11.0-8.el8_4.15, tigervnc-selinux 1.11.0-8.el8_4.15, +9 more
    fixed: vendor fix RHSA-2026:23254
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) tigervnc 1.12.0-6.el8_6.17, tigervnc-icons 1.12.0-6.el8_6.17, tigervnc-server 1.12.0-6.el8_6.17, tigervnc-license 1.12.0-6.el8_6.17, tigervnc-selinux 1.12.0-6.el8_6.17, tigervnc-server-module 1.12.0-6.el8_6.17, +1 more
    fixed: vendor fix RHSA-2026:24341
  • Red Hat Enterprise Linux AppStream TUS (v.8.6) xorg-x11-server 1.20.11-7.el8_6, xorg-x11-server-Xdmx 1.20.11-7.el8_6, xorg-x11-server-Xorg 1.20.11-7.el8_6, xorg-x11-server-Xvfb 1.20.11-7.el8_6, xorg-x11-server-Xnest 1.20.11-7.el8_6, xorg-x11-server-common 1.20.11-7.el8_6, +2 more
    fixed: vendor fix RHSA-2026:21718
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) tigervnc 1.12.0-15.el8_8.17, xorg-x11-server 1.20.11-18.el8_8, tigervnc-icons 1.12.0-15.el8_8.17, tigervnc-server 1.12.0-15.el8_8.17, tigervnc-license 1.12.0-15.el8_8.17, tigervnc-selinux 1.12.0-15.el8_8.17, +9 more
    fixed: vendor fix RHSA-2026:23255
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) xorg-x11-server-source 1.20.11-33.el9_7, xorg-x11-server-source 1.20.11-34.el9_8, xorg-x11-server-Xwayland 23.2.7-6.el9_7, xorg-x11-server-Xwayland 24.1.9-4.el9_8
    fixed: vendor fix RHSA-2026:11388
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) xorg-x11-server-Xwayland-devel 24.1.5-6.el10_1, xorg-x11-server-Xwayland-devel 24.1.9-4.el10_2, xorg-x11-server-Xwayland-debuginfo 24.1.5-6.el10_1, xorg-x11-server-Xwayland-debuginfo 24.1.9-4.el10_2, xorg-x11-server-Xwayland-debugsource 24.1.5-6.el10_1, xorg-x11-server-Xwayland-debugsource 24.1.9-4.el10_2
    fixed: vendor fix RHSA-2026:11352
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) xorg-x11-server-Xwayland-devel 24.1.5-6.el10_0, xorg-x11-server-Xwayland-debuginfo 24.1.5-6.el10_0, xorg-x11-server-Xwayland-debugsource 24.1.5-6.el10_0
    fixed: vendor fix RHSA-2026:20563
  • Red Hat Enterprise Linux CRB (v. 8) xorg-x11-server-source 1.20.11-28.el8_10
    fixed: vendor fix RHSA-2026:11692
  • Red Hat Enterprise Linux Server -EXTENSION(v. 6 ELS-EXTENSION) tigervnc 1.1.0-25.el6_10.16, tigervnc-server 1.1.0-25.el6_10.16
    fixed: vendor fix RHSA-2026:23496
  • Red Hat Enterprise Linux Server (v. 7 ELS) tigervnc 1.8.0-36.el7_9.4, tigervnc-icons 1.8.0-36.el7_9.4, xorg-x11-server 1.20.4-34.el7_9, tigervnc-server 1.8.0-36.el7_9.4, tigervnc-license 1.8.0-36.el7_9.4, xorg-x11-server-Xorg 1.20.4-34.el7_9, +3 more
    fixed: vendor fix RHSA-2026:22456
  • Red Hat Enterprise Linux Server Optional -EXTENSION (v. 6 ELS -EXTENSION) tigervnc-server-applet 1.1.0-25.el6_10.16, tigervnc-server-module 1.1.0-25.el6_10.16
    fixed: vendor fix RHSA-2026:23496
  • Red Hat Enterprise Linux Server Optional (v. 7 ELS) xorg-x11-server-Xdmx 1.20.4-34.el7_9, xorg-x11-server-Xvfb 1.20.4-34.el7_9, xorg-x11-server-Xnest 1.20.4-34.el7_9, xorg-x11-server-source 1.20.4-34.el7_9, tigervnc-server-applet 1.8.0-36.el7_9.4, tigervnc-server-module 1.8.0-36.el7_9.4, +1 more
    fixed: vendor fix RHSA-2026:22456

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
6 mo ago

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 18% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA ADP 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION
  • Red Hat Red Hat Enterprise Linux 7 Extended Lifecycle Support
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  • Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
  • Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
  • Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
  • Red Hat Red Hat Enterprise Linux 8.6 Telecommunications Update Service
  • Red Hat Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service
  • Red Hat Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions
  • Red Hat Red Hat Enterprise Linux 9.4 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
  • Red Hat Red Hat Enterprise Linux 6

Classification

Weakness
  • CWE-825 Expired Pointer Dereference

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.