A critical security update addresses multiple vulnerabilities in the xorg-x11-server package, including use-after-free, out-of-bounds reads, and integer underflow flaws in XKB handling, which can lead to denial of service, information disclosure, or memory corruption. The CVSS scores for the primary CVEs range from 6.1 (MEDIUM) to 7.8 (HIGH). Affected systems are specifically Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions and Telecommunications Update Service; the NVD data indicates broader affected versions include RHEL 6.0, 7.0, 8.0, and 9.0.
Red Hat Product Errata RHSA-2026:21742 - Security Advisory Issued: 2026-05-28 Updated: 2026-05-28 RHSA-2026:21742 - 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 8.8 Update Services for SAP Solutions and Red Hat Enterprise Linux 8.8 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 Update Support Extension 8.8 x86_64 Red Hat Enterprise Linux Server - TUS 8.8 x86_64 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 8.8 ppc64le Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 8.8 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 8.8 SRPM xorg-x11-server-1.20.11-18.el8_8.src.rpm SHA-256: 3cbdb3955a9ab9ac19dce86fd76b58c0872566462e80ed1c0cb15cd1b6a9c0f1 x86_64 xorg-x11-server-Xdmx-1.20.11-18.el8_8.x86_64.rpm SHA-256: ccfa89a0e3c0eb28627b9566a811fadc0a7b63d6f402257bad64f396fd18f263 xorg-x11-server-Xdmx-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: 2d05cfd3b0506e92be73dbe80b60418b52010f371f74dd65e40f23f8986ff8ef xorg-x11-server-Xephyr-1.20.11-18.el8_8.x86_64.rpm SHA-256: e7c4bfc156865a73873e81850a5dd5332f1795284f3172590df2719b1d30d9dd xorg-x11-server-Xephyr-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: dadf7ac30ddd4c6487d725c7bccbd5f76da866325d6296287e586f4e856bad04 xorg-x11-server-Xnest-1.20.11-18.el8_8.x86_64.rpm SHA-256: 45e88cfbc5cd30976f4e857df2433d17fed69df402287b9d44b3167387da9e62 xorg-x11-server-Xnest-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: a590e06f277386ced65b69fed16153978dd8c8652b1974aa56657d55313ac8e0 xorg-x11-server-Xorg-1.20.11-18.el8_8.x86_64.rpm SHA-256: 91b53bae7c289a37494efaff87a3f4e46b21ebe4ea5f910212c0b77a9c621e4d xorg-x11-server-Xorg-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: 41d0583b0cbf6e1504b72e5dd7b82cb70f6ca5434a82336c46b71742e460eb7a xorg-x11-server-Xvfb-1.20.11-18.el8_8.x86_64.rpm SHA-256: e677981534ff5a9b49d8540c5527c7a079ceac37e1eff936af60219b4e12556f xorg-x11-server-Xvfb-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: 2314d8671c8dea3a454663037eb7ef915e2b9f211601714b51aa81f499d37513 xorg-x11-server-common-1.20.11-18.el8_8.x86_64.rpm SHA-256: 5b789b01c0bcc24b1e9f783f186764d403ab94d098c65347cfcdf7352a9c3a89 xorg-x11-server-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: 97509274fbda5d3da546ba461a8934dc64fed1c162d928a58601a6def5dff029 xorg-x11-server-debugsource-1.20.11-18.el8_8.x86_64.rpm SHA-256: c789c0863b90b68e88ed28be106b1d5bafae39f4b1a9170fdc094f78d92b5808 Red Hat Enterprise Linux Server - TUS 8.8 SRPM xorg-x11-server-1.20.11-18.el8_8.src.rpm SHA-256: 3cbdb3955a9ab9ac19dce86fd76b58c0872566462e80ed1c0cb15cd1b6a9c0f1 x86_64 xorg-x11-server-Xdmx-1.20.11-18.el8_8.x86_64.rpm SHA-256: ccfa89a0e3c0eb28627b9566a811fadc0a7b63d6f402257bad64f396fd18f263 xorg-x11-server-Xdmx-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: 2d05cfd3b0506e92be73dbe80b60418b52010f371f74dd65e40f23f8986ff8ef xorg-x11-server-Xephyr-1.20.11-18.el8_8.x86_64.rpm SHA-256: e7c4bfc156865a73873e81850a5dd5332f1795284f3172590df2719b1d30d9dd xorg-x11-server-Xephyr-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: dadf7ac30ddd4c6487d725c7bccbd5f76da866325d6296287e586f4e856bad04 xorg-x11-server-Xnest-1.20.11-18.el8_8.x86_64.rpm SHA-256: 45e88cfbc5cd30976f4e857df2433d17fed69df402287b9d44b3167387da9e62 xorg-x11-server-Xnest-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: a590e06f277386ced65b69fed16153978dd8c8652b1974aa56657d55313ac8e0 xorg-x11-server-Xorg-1.20.11-18.el8_8.x86_64.rpm SHA-256: 91b53bae7c289a37494efaff87a3f4e46b21ebe4ea5f910212c0b77a9c621e4d xorg-x11-server-Xorg-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: 41d0583b0cbf6e1504b72e5dd7b82cb70f6ca5434a82336c46b71742e460eb7a xorg-x11-server-Xvfb-1.20.11-18.el8_8.x86_64.rpm SHA-256: e677981534ff5a9b49d8540c5527c7a079ceac37e1eff936af60219b4e12556f xorg-x11-server-Xvfb-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: 2314d8671c8dea3a454663037eb7ef915e2b9f211601714b51aa81f499d37513 xorg-x11-server-common-1.20.11-18.el8_8.x86_64.rpm SHA-256: 5b789b01c0bcc24b1e9f783f186764d403ab94d098c65347cfcdf7352a9c3a89 xorg-x11-server-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: 97509274fbda5d3da546ba461a8934dc64fed1c162d928a58601a6def5dff029 xorg-x11-server-debugsource-1.20.11-18.el8_8.x86_64.rpm SHA-256: c789c0863b90b68e88ed28be106b1d5bafae39f4b1a9170fdc094f78d92b5808 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 8.8 SRPM xorg-x11-server-1.20.11-18.el8_8.src.rpm SHA-256: 3cbdb3955a9ab9ac19dce86fd76b58c0872566462e80ed1c0cb15cd1b6a9c0f1 ppc64le xorg-x11-server-Xdmx-1.20.11-18.el8_8.ppc64le.rpm SHA-256: da822cd73f4a6659a2cb3e87acdf0fafb76f315415a609801d59025da4b147be xorg-x11-server-Xdmx-debuginfo-1.20.11-18.el8_8.ppc64le.rpm SHA-256: 2841921639994e1949f61f47f74b052d5b29b0ef7c81126b81433d09736cbe48 xorg-x11-server-Xephyr-1.20.11-18.el8_8.ppc64le.rpm SHA-256: 330883b479bc4b361de6f82a86b3d12ca9dff8a8b8b0bac19e2ded3e42d2f665 xorg-x11-server-Xephyr-debuginfo-1.20.11-18.el8_8.ppc64le.rpm SHA-256: 0f3009ac68dd3284fb0ba87c65c95f42a1c38ca14b429968bf97f7654132c071 xorg-x11-server-Xnest-1.20.11-18.el8_8.ppc64le.rpm SHA-256: e78a4a7f323cf672a341bdaabbb2b41a15853eb7da2053607012857dd5ffba96 xorg-x11-server-Xnest-debuginfo-1.20.11-18.el8_8.ppc64le.rpm SHA-256: 1499c38fe0e52230930078d1d7e78c1e74ae48d8fececfc7f8564277604428ef xorg-x11-server-Xorg-1.20.11-18.el8_8.ppc64le.rpm SHA-256: 84d964a9f05844a4afe78b83bcfc421dcde153207668c4fff4467358c494f2c2 xorg-x11-server-Xorg-debuginfo-1.20.11-18.el8_8.ppc64le.rpm SHA-256: bb9fc718a6a41882c0a61acdd6d14a27cc577fc8515f10cdbcdb75aeca013645 xorg-x11-server-Xvfb-1.20.11-18.el8_8.ppc64le.rpm SHA-256: 4869dabacbcccf84f64926da41e7c941c4a68ef3aa152cd571e576d126dd93a2 xorg-x11-server-Xvfb-debuginfo-1.20.11-18.el8_8.ppc64le.rpm SHA-256: 64cbad5917724133c9cac7b654dbe526269a77a37523d8c86653887407fca257 xorg-x11-server-common-1.20.11-18.el8_8.ppc64le.rpm SHA-256: fc9a228472209ca41879b1c022788fdc92a7a47e0ecaf00ae22dd4f86468345b xorg-x11-server-debuginfo-1.20.11-18.el8_8.ppc64le.rpm SHA-256: 1ea211cbbb66b5efebb7508edd837089b39670471d63f5eeafb60effcfcdf345 xorg-x11-server-debugsource-1.20.11-18.el8_8.ppc64le.rpm SHA-256: ec2824177079c06f276f43dbd49fcdac6166a36be13acfd411d02ed93d15e638 Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 8.8 SRPM xorg-x11-server-1.20.11-18.el8_8.src.rpm SHA-256: 3cbdb3955a9ab9ac19dce86fd76b58c0872566462e80ed1c0cb15cd1b6a9c0f1 x86_64 xorg-x11-server-Xdmx-1.20.11-18.el8_8.x86_64.rpm SHA-256: ccfa89a0e3c0eb28627b9566a811fadc0a7b63d6f402257bad64f396fd18f263 xorg-x11-server-Xdmx-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: 2d05cfd3b0506e92be73dbe80b60418b52010f371f74dd65e40f23f8986ff8ef xorg-x11-server-Xephyr-1.20.11-18.el8_8.x86_64.rpm SHA-256: e7c4bfc156865a73873e81850a5dd5332f1795284f3172590df2719b1d30d9dd xorg-x11-server-Xephyr-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: dadf7ac30ddd4c6487d725c7bccbd5f76da866325d6296287e586f4e856bad04 xorg-x11-server-Xnest-1.20.11-18.el8_8.x86_64.rpm SHA-256: 45e88cfbc5cd30976f4e857df2433d17fed69df402287b9d44b3167387da9e62 xorg-x11-server-Xnest-debuginfo-1.20.11-18.el8_8.x86_64.rpm SHA-256: a590e06f277386ced65b69fed16153978dd8c8652b1974aa56657d55313ac8e0 xorg-x11-server-Xorg-1.20.11-18.el8_8.x86_64.rp