RHSA-2026:21718 - Security Advisory

Topic

An update for xorg-x11-server is now available for Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support, Red Hat Enterprise Linux 8.6 Update Services for SAP Solutions, and Red Hat Enterprise Linux 8.6 Telecommunications Update Service.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

X.Org is an open-source implementation of the X Window System. It provides the basic low-level functionality that full-fledged graphical user interfaces are designed upon.

Security Fix(es):

• xorg: xwayland: X.Org X server: Denial of Service via integer underflow in XKB compatibility map handling (CVE-2026-33999)
• xwayland: xorg: X.Org X server: Information disclosure and denial of service via out-of-bounds read in XKB geometry processing. (CVE-2026-34000)
• xorg: xwayland: X.Org X server: Use-after-free vulnerability leads to server crash and potential memory corruption (CVE-2026-34001)
• xorg: xwayland: X.Org X server: Information disclosure or Denial of Service via out-of-bounds read in XKB modifier map handling (CVE-2026-34002)
• xorg: xwayland: X.Org X server: Information exposure and denial of service via out-of-bounds memory access (CVE-2026-34003)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle Long Life 8.6 x86_64
• Red Hat Enterprise Linux Server - AUS 8.6 x86_64
• Red Hat Enterprise Linux Server - TUS 8.6 x86_64
• Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 8.6 ppc64le
• Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 8.6 x86_64
• Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle Long Life 8.6 aarch64
• Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle Long Life 8.6 ppc64le
• Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle Long Life 8.6 s390x

Fixes

• BZ - 2451106 - CVE-2026-33999 xorg: xwayland: X.Org X server: Denial of Service via integer underflow in XKB compatibility map handling
• BZ - 2451107 - CVE-2026-34000 xwayland: xorg: X.Org X server: Information disclosure and denial of service via out-of-bounds read in XKB geometry processing.
• BZ - 2451109 - CVE-2026-34001 xorg: xwayland: X.Org X server: Use-after-free vulnerability leads to server crash and potential memory corruption
• BZ - 2451112 - CVE-2026-34002 xorg: xwayland: X.Org X server: Information disclosure or Denial of Service via out-of-bounds read in XKB modifier map handling
• BZ - 2451113 - CVE-2026-34003 xorg: xwayland: X.Org X server: Information exposure and denial of service via out-of-bounds memory access

CVEs

• CVE-2026-33999
• CVE-2026-34000
• CVE-2026-34001
• CVE-2026-34002
• CVE-2026-34003

References

• https://access.redhat.com/security/updates/classification/#important