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Vulnerability · Published Apr 23, 2026 · Assigned by redhat

CVE-2026-33999Xorg: xwayland: x.org x server: denial of service via integer underflow in xkb compatibility map handling

High 7.8

In plain English

A high-severity security flaw in Red Hat Enterprise Linux 10 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.8High
Exploit odds (30 days)0.4%top 67.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

A flaw was found in the X.Org X server. This integer underflow vulnerability, specifically in the XKB compatibility map handling, allows an attacker with local or remote X11 server access to trigger a buffer read overrun. This can lead to memory-safety violations and potentially a denial of service (DoS) or other severe impacts.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:8tigervnc1.15.0-9.el8_10ALSA-2026:13414
AlmaLinux:9tigervnc1.15.0-6.el9_7.1ALSA-2026:10739
AlmaLinux:9tigervnc1.15.0-7.el9_8.1ALSA-2026:19342
AlmaLinux:8tigervnc-icons1.15.0-9.el8_10ALSA-2026:13414
AlmaLinux:9tigervnc-icons1.15.0-7.el9_8.1ALSA-2026:19342
AlmaLinux:9tigervnc-icons1.15.0-6.el9_7.1ALSA-2026:10739
AlmaLinux:8tigervnc-license1.15.0-9.el8_10ALSA-2026:13414
AlmaLinux:9tigervnc-license1.15.0-6.el9_7.1ALSA-2026:10739
AlmaLinux:9tigervnc-license1.15.0-7.el9_8.1ALSA-2026:19342
AlmaLinux:8tigervnc-selinux1.15.0-9.el8_10ALSA-2026:13414
AlmaLinux:9tigervnc-selinux1.15.0-7.el9_8.1ALSA-2026:19342
AlmaLinux:9tigervnc-selinux1.15.0-6.el9_7.1ALSA-2026:10739
AlmaLinux:8tigervnc-server1.15.0-9.el8_10ALSA-2026:13414
AlmaLinux:9tigervnc-server1.15.0-7.el9_8.1ALSA-2026:19342
AlmaLinux:9tigervnc-server1.15.0-6.el9_7.1ALSA-2026:10739
AlmaLinux:8tigervnc-server-minimal1.15.0-9.el8_10ALSA-2026:13414
AlmaLinux:9tigervnc-server-minimal1.15.0-6.el9_7.1ALSA-2026:10739
AlmaLinux:9tigervnc-server-minimal1.15.0-7.el9_8.1ALSA-2026:19342
AlmaLinux:8tigervnc-server-module1.15.0-9.el8_10ALSA-2026:13414
AlmaLinux:9tigervnc-server-module1.15.0-6.el9_7.1ALSA-2026:10739
AlmaLinux:9tigervnc-server-module1.15.0-7.el9_8.1ALSA-2026:19342
AlmaLinux:8xorg-x11-server-Xdmx1.20.11-28.el8_10ALSA-2026:11692
AlmaLinux:9xorg-x11-server-Xdmx1.20.11-34.el9_8ALSA-2026:19343
AlmaLinux:9xorg-x11-server-Xdmx1.20.11-33.el9_7ALSA-2026:11388
AlmaLinux:8xorg-x11-server-Xephyr1.20.11-28.el8_10ALSA-2026:11692
AlmaLinux:9xorg-x11-server-Xephyr1.20.11-33.el9_7ALSA-2026:11388
AlmaLinux:9xorg-x11-server-Xephyr1.20.11-34.el9_8ALSA-2026:19343
AlmaLinux:8xorg-x11-server-Xnest1.20.11-28.el8_10ALSA-2026:11692
AlmaLinux:9xorg-x11-server-Xnest1.20.11-33.el9_7ALSA-2026:11388
AlmaLinux:9xorg-x11-server-Xnest1.20.11-34.el9_8ALSA-2026:19343
AlmaLinux:8xorg-x11-server-Xorg1.20.11-28.el8_10ALSA-2026:11692
AlmaLinux:9xorg-x11-server-Xorg1.20.11-34.el9_8ALSA-2026:19343
AlmaLinux:9xorg-x11-server-Xorg1.20.11-33.el9_7ALSA-2026:11388
AlmaLinux:8xorg-x11-server-Xvfb1.20.11-28.el8_10ALSA-2026:11692
AlmaLinux:9xorg-x11-server-Xvfb1.20.11-33.el9_7ALSA-2026:11388
AlmaLinux:9xorg-x11-server-Xvfb1.20.11-34.el9_8ALSA-2026:19343
AlmaLinux:10xorg-x11-server-Xwayland24.1.5-6.el10_1ALSA-2026:11352
AlmaLinux:10xorg-x11-server-Xwayland24.1.9-4.el10_2ALSA-2026:19125
AlmaLinux:8xorg-x11-server-Xwayland21.1.3-20.el8_10ALSA-2026:11656
AlmaLinux:9xorg-x11-server-Xwayland24.1.9-4.el9_8ALSA-2026:19344
AlmaLinux:9xorg-x11-server-Xwayland23.2.7-6.el9_7ALSA-2026:11369
AlmaLinux:10xorg-x11-server-Xwayland-devel24.1.9-4.el10_2ALSA-2026:19125
AlmaLinux:10xorg-x11-server-Xwayland-devel24.1.5-6.el10_1ALSA-2026:11352
AlmaLinux:9xorg-x11-server-Xwayland-devel24.1.9-4.el9_8ALSA-2026:19344
AlmaLinux:9xorg-x11-server-Xwayland-devel23.2.7-6.el9_7ALSA-2026:11369
AlmaLinux:8xorg-x11-server-common1.20.11-28.el8_10ALSA-2026:11692
AlmaLinux:9xorg-x11-server-common1.20.11-34.el9_8ALSA-2026:19343
AlmaLinux:9xorg-x11-server-common1.20.11-33.el9_7ALSA-2026:11388
AlmaLinux:8xorg-x11-server-devel1.20.11-28.el8_10ALSA-2026:11692
AlmaLinux:9xorg-x11-server-devel1.20.11-33.el9_7ALSA-2026:11388
AlmaLinux:9xorg-x11-server-devel1.20.11-34.el9_8ALSA-2026:19343
AlmaLinux:8xorg-x11-server-source1.20.11-28.el8_10ALSA-2026:11692
AlmaLinux:9xorg-x11-server-source1.20.11-34.el9_8ALSA-2026:19343
AlmaLinux:9xorg-x11-server-source1.20.11-33.el9_7ALSA-2026:11388
Alpine:v3.23xorg-server21.1.22-r0ALPINE-CVE-2026-33999
Alpine:v3.24xorg-server21.1.22-r0ALPINE-CVE-2026-33999
Alpine:v3.23xwayland24.1.10-r0ALPINE-CVE-2026-33999
Alpine:v3.24xwayland24.1.10-r0ALPINE-CVE-2026-33999
Debian:12xorg-server2:21.1.7-3+deb12u12DEBIAN-CVE-2026-33999
Debian:13xorg-server2:21.1.16-1.3+deb13u2DEBIAN-CVE-2026-33999
Debian:14xorg-server2:21.1.22-1DEBIAN-CVE-2026-33999
Debian:12xwaylandno fix listedDEBIAN-CVE-2026-33999
Debian:13xwaylandno fix listedDEBIAN-CVE-2026-33999
Debian:14xwayland2:24.1.10-1DEBIAN-CVE-2026-33999
Rocky Linux:8tigervnc0:1.15.0-9.el8_10RLSA-2026:13414
Rocky Linux:9tigervnc0:1.15.0-6.el9_7.1RLSA-2026:10739
Rocky Linux:9tigervnc0:1.15.0-7.el9_8.1RLSA-2026:19342
Rocky Linux:8xorg-x11-server0:1.20.11-28.el8_10RLSA-2026:11692
Rocky Linux:9xorg-x11-server0:1.20.11-34.el9_8RLSA-2026:19343
Rocky Linux:9xorg-x11-server0:1.20.11-33.el9_7RLSA-2026:11388
Rocky Linux:10xorg-x11-server-Xwayland0:24.1.5-6.el10_1RLSA-2026:11352
Rocky Linux:10xorg-x11-server-Xwayland0:24.1.9-4.el10_2RLSA-2026:19125
Rocky Linux:8xorg-x11-server-Xwayland0:21.1.3-20.el8_10RLSA-2026:11656
Rocky Linux:9xorg-x11-server-Xwayland0:24.1.9-4.el9_8RLSA-2026:19344
Rocky Linux:9xorg-x11-server-Xwayland0:23.2.7-6.el9_7RLSA-2026:11369
Ubuntu:22.04:LTSxorg-serverno fix listedUBUNTU-CVE-2026-33999
Ubuntu:24.04:LTSxorg-serverno fix listedUBUNTU-CVE-2026-33999
Ubuntu:25.10xorg-serverno fix listedUBUNTU-CVE-2026-33999
Ubuntu:26.04:LTSxorg-serverno fix listedUBUNTU-CVE-2026-33999
Ubuntu:26.10xorg-serverno fix listedUBUNTU-CVE-2026-33999
Ubuntu:22.04:LTSxwaylandno fix listedUBUNTU-CVE-2026-33999
Ubuntu:24.04:LTSxwaylandno fix listedUBUNTU-CVE-2026-33999
Ubuntu:25.10xwaylandno fix listedUBUNTU-CVE-2026-33999
Ubuntu:26.04:LTSxwaylandno fix listedUBUNTU-CVE-2026-33999
Ubuntu:26.10xwaylandno fix listedUBUNTU-CVE-2026-33999

Affected products (as reported)

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

Weakness: CWE-191 · Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References