A series of vulnerabilities in the X.Org X server, primarily affecting XWayland, include integer underflows, out-of-bounds reads, and use-after-free conditions (CVE-2026-33999, CVSS 7.8 HIGH; CVE-2026-34000, CVSS 6.1 MEDIUM; CVE-2026-34001, CVSS 7.8 HIGH) that can lead to denial of service, information disclosure, and potential memory corruption. The affected versions include x.org x_server up to an unspecified version and Red Hat Enterprise Linux versions 6.0, 7.0, 8.0, and 9.0. Red Hat has released an important security update for xorg-x11-server to address these issues for RHEL 8.4 Advanced Mission Critical and Extended Update Support subscribers.
Red Hat Product Errata RHSA-2026:21715 - Security Advisory Issued: 2026-05-28 Updated: 2026-05-28 RHSA-2026:21715 - Security Advisory Overview Updated Packages Synopsis Important: xorg-x11-server security update Type/Severity Security Advisory: Important Red Hat Lightspeed patch analysis Identify and remediate systems affected by this advisory. View affected systems Topic An update for xorg-x11-server is now available for Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On. 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 Update Support Extension 8.4 x86_64 Red Hat Enterprise Linux Server - AUS 8.4 x86_64 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 Note: More recent versions of these packages may be available. Click a package name for more details. Red Hat Enterprise Linux for x86_64 - Extended Update Support Extension 8.4 SRPM xorg-x11-server-1.20.10-4.el8_4.src.rpm SHA-256: 607828f0aff02c865d4bbda7fdf2158fe074b51a2ea57c16c1a618d951f14283 x86_64 xorg-x11-server-Xdmx-1.20.10-4.el8_4.x86_64.rpm SHA-256: bafc1f548433b2af63a274a9689c6d831c37f489834f76fbe63e0430a6462e03 xorg-x11-server-Xdmx-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 6329dc12f5f7ad6d05ef6ac77d1d4fc80fc51e2a68067fd401aab4efcd24f03b xorg-x11-server-Xephyr-1.20.10-4.el8_4.x86_64.rpm SHA-256: b52a742835aa2d2c9ff4db54965fb6c567007840d9048ce3360934e17fbf2cb2 xorg-x11-server-Xephyr-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 1c4b48b13b6f2e80f8caf528424cc74de6d42685dede53ea11a421811bd9680a xorg-x11-server-Xnest-1.20.10-4.el8_4.x86_64.rpm SHA-256: ae53d19b624f697c226fb542878795d713785a3b6a916973016693b08f53be86 xorg-x11-server-Xnest-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 90b35f37430503c893fbcb81afe360053740a6839a0091f346c6cef059e1ad3c xorg-x11-server-Xorg-1.20.10-4.el8_4.x86_64.rpm SHA-256: 5cfb45541fde251a288f34dc617c1d84f2a12f56cd323971c9065b3efa28be85 xorg-x11-server-Xorg-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 61f79e47f573fb2d007260b68764a5a22b4f9317b9cbbd4d644eccd9f6953681 xorg-x11-server-Xvfb-1.20.10-4.el8_4.x86_64.rpm SHA-256: 07e4ca8d9e11512aa61ef891a346a248b682df74ce9ab6dcc35e042ff09fd089 xorg-x11-server-Xvfb-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: a79f9489b7b6f863cd6a3db836188256d871409c75c8b40b7bc339a0295e4e77 xorg-x11-server-Xwayland-1.20.10-4.el8_4.x86_64.rpm SHA-256: 5d2944ca21394574805f07033ddd81c6872eb88cf20c49998f680ff6119c9da4 xorg-x11-server-Xwayland-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 314f96c8a8269754cc05fa11bb6108d92ae9d61ae2404c6b7f7b7a2d8aa1f45f xorg-x11-server-common-1.20.10-4.el8_4.x86_64.rpm SHA-256: 5fd528efca84c8384b0b4e29843eac0e52e9bdc3234ffe17248aedc4d05754a0 xorg-x11-server-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: cbd148def6818fc5f2af5be1153eb71e36d78673aff3ad1dceb906eeaf6b52d7 xorg-x11-server-debugsource-1.20.10-4.el8_4.x86_64.rpm SHA-256: b3b1e30f1e90c279f91465c34631e18f99fb81b04c2fcee7acdaf8e1d6fbccd3 Red Hat Enterprise Linux Server - AUS 8.4 SRPM xorg-x11-server-1.20.10-4.el8_4.src.rpm SHA-256: 607828f0aff02c865d4bbda7fdf2158fe074b51a2ea57c16c1a618d951f14283 x86_64 xorg-x11-server-Xdmx-1.20.10-4.el8_4.x86_64.rpm SHA-256: bafc1f548433b2af63a274a9689c6d831c37f489834f76fbe63e0430a6462e03 xorg-x11-server-Xdmx-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 6329dc12f5f7ad6d05ef6ac77d1d4fc80fc51e2a68067fd401aab4efcd24f03b xorg-x11-server-Xephyr-1.20.10-4.el8_4.x86_64.rpm SHA-256: b52a742835aa2d2c9ff4db54965fb6c567007840d9048ce3360934e17fbf2cb2 xorg-x11-server-Xephyr-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 1c4b48b13b6f2e80f8caf528424cc74de6d42685dede53ea11a421811bd9680a xorg-x11-server-Xnest-1.20.10-4.el8_4.x86_64.rpm SHA-256: ae53d19b624f697c226fb542878795d713785a3b6a916973016693b08f53be86 xorg-x11-server-Xnest-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 90b35f37430503c893fbcb81afe360053740a6839a0091f346c6cef059e1ad3c xorg-x11-server-Xorg-1.20.10-4.el8_4.x86_64.rpm SHA-256: 5cfb45541fde251a288f34dc617c1d84f2a12f56cd323971c9065b3efa28be85 xorg-x11-server-Xorg-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 61f79e47f573fb2d007260b68764a5a22b4f9317b9cbbd4d644eccd9f6953681 xorg-x11-server-Xvfb-1.20.10-4.el8_4.x86_64.rpm SHA-256: 07e4ca8d9e11512aa61ef891a346a248b682df74ce9ab6dcc35e042ff09fd089 xorg-x11-server-Xvfb-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: a79f9489b7b6f863cd6a3db836188256d871409c75c8b40b7bc339a0295e4e77 xorg-x11-server-Xwayland-1.20.10-4.el8_4.x86_64.rpm SHA-256: 5d2944ca21394574805f07033ddd81c6872eb88cf20c49998f680ff6119c9da4 xorg-x11-server-Xwayland-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: 314f96c8a8269754cc05fa11bb6108d92ae9d61ae2404c6b7f7b7a2d8aa1f45f xorg-x11-server-common-1.20.10-4.el8_4.x86_64.rpm SHA-256: 5fd528efca84c8384b0b4e29843eac0e52e9bdc3234ffe17248aedc4d05754a0 xorg-x11-server-debuginfo-1.20.10-4.el8_4.x86_64.rpm SHA-256: cbd148def6818fc5f2af5be1153eb71e36d78673aff3ad1dceb906eeaf6b52d7 xorg-x11-server-debugsource-1.20.10-4.el8_4.x86_64.rpm SHA-256: b3b1e30f1e90c279f91465c34631e18f99fb81b04c2fcee7acdaf8e1d6fbccd3 The Red Hat security contact is secalert@redhat.com . 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