This security update addresses multiple vulnerabilities in the xorg-x11-server, including use-after-free, out-of-bounds reads, and integer underflow issues within XKB handling, which can lead to denial of service, information disclosure, or memory corruption. The CVSS scores for the primary vulnerabilities are 7.8 (HIGH) for CVE-2026-33999 and CVE-2026-34001, and 6.1 (MEDIUM) for CVE-2026-34000. Affected versions include Red Hat Enterprise Linux 6.0, 7.0, 8.0, and 9.0, and administrators should apply the referenced Red Hat security patch for their specific distribution.
Red Hat Product Errata RHSA-2026:20557 - Security Advisory Issued: 2026-05-26 Updated: 2026-05-26 RHSA-2026:20557 - 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 9.2 Update Services for SAP Solutions. 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 Server - AUS 9.2 x86_64 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.2 ppc64le Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.2 x86_64 Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.2 aarch64 Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.2 s390x Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.2 x86_64 Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.2 aarch64 Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.2 ppc64le Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.2 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 Note: More recent versions of these packages may be available. Click a package name for more details. Red Hat Enterprise Linux Server - AUS 9.2 SRPM xorg-x11-server-1.20.11-20.el9_2.src.rpm SHA-256: d9be5b53bf270256204278f0338babbd00760d61d7b6ca9ec8ed281535556f76 x86_64 xorg-x11-server-Xdmx-1.20.11-20.el9_2.x86_64.rpm SHA-256: f1dddbe39de5d3ce39cd6bd98b93525f2db8bc1ea2b03fc5445bc61cddf3041d xorg-x11-server-Xdmx-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: 448b675762b3887ebeb855c5e238bbffc63594ec5a1dd3198a9105b90a234efe xorg-x11-server-Xephyr-1.20.11-20.el9_2.x86_64.rpm SHA-256: 4e78505558e1ba30c567aaabd7eab379af2408f8d3e8400e2f482ea6308b82e5 xorg-x11-server-Xephyr-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: 83f356f1223e8f9cbbf8fd35342c24e4f2b870d9ec9792ef524365a2c2fb07a4 xorg-x11-server-Xnest-1.20.11-20.el9_2.x86_64.rpm SHA-256: 9faf4b90616ccd1e436f58eac3f400e50979b9749bebf14b8037e80402ad9b62 xorg-x11-server-Xnest-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: d042cc38fc5a0db3913e7c3b49d6acec3613d3e07927dd114d2ae9d3122e724d xorg-x11-server-Xorg-1.20.11-20.el9_2.x86_64.rpm SHA-256: 87c6e507ab03bfce1447ac468c788fbc8211fecfcf0f4671fb917353d23eef0e xorg-x11-server-Xorg-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: 4f3cfa20c6db302aeb380b9581a77a1e80352395557cb6ecaef5c0d657dff226 xorg-x11-server-Xvfb-1.20.11-20.el9_2.x86_64.rpm SHA-256: 19140d8b7e4ed7d1026795c20e07910f8883a4bfc32eb38ef56d894ec3b3f526 xorg-x11-server-Xvfb-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: c788537b154131e0d07ff7fa11b7da4666c8ae1579664937a4c5ad46c88f9a8c xorg-x11-server-common-1.20.11-20.el9_2.x86_64.rpm SHA-256: 19e9cbc1ac5fd2a41ba31768f0a5b7caf95c43ee471e2d46b42d09ce531c1c81 xorg-x11-server-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: 6025b9161a45207022c54da569af9ab05d612b5ee269cb520b7896a5d42bab1b xorg-x11-server-debugsource-1.20.11-20.el9_2.x86_64.rpm SHA-256: ea946e3b6e462c2947f109bb7afe01c3409ad1fb7ec431bd469d1756d8126568 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.2 SRPM xorg-x11-server-1.20.11-20.el9_2.src.rpm SHA-256: d9be5b53bf270256204278f0338babbd00760d61d7b6ca9ec8ed281535556f76 ppc64le xorg-x11-server-Xdmx-1.20.11-20.el9_2.ppc64le.rpm SHA-256: 3158bfe93d06080247f7954b0920f3b02f9a78a5bf89c7f5ef268b2955dd0a85 xorg-x11-server-Xdmx-debuginfo-1.20.11-20.el9_2.ppc64le.rpm SHA-256: 9414f7d26beda170b20d270c966aee35ca05ff1b6ad4759333c5067f101ce513 xorg-x11-server-Xephyr-1.20.11-20.el9_2.ppc64le.rpm SHA-256: 2d18817af0fd1e9227d486b21f1f02fdf3a2df45ad2c6c49c6ed8deaeadadab5 xorg-x11-server-Xephyr-debuginfo-1.20.11-20.el9_2.ppc64le.rpm SHA-256: f2fb02d42036e3193a2210676993c0dfe3bf6a2312f056a921e3267a0d7061ca xorg-x11-server-Xnest-1.20.11-20.el9_2.ppc64le.rpm SHA-256: e18f08702b3499949a012527d9666f0ebc63c1c693396da9caebba14f3fc9e2f xorg-x11-server-Xnest-debuginfo-1.20.11-20.el9_2.ppc64le.rpm SHA-256: 0fc5241fbaa51a466281afe54d7fcd9722be19fd50f28a2d764b81a211ed20f8 xorg-x11-server-Xorg-1.20.11-20.el9_2.ppc64le.rpm SHA-256: 61db6e6ffe889010604003a70fb06b939e34bf8be5296bb823d7af1dcf8d3bcc xorg-x11-server-Xorg-debuginfo-1.20.11-20.el9_2.ppc64le.rpm SHA-256: b2a2f6f7dc4050902e9d303b52719d41716665adb9552aaa81b5a4dea0d56031 xorg-x11-server-Xvfb-1.20.11-20.el9_2.ppc64le.rpm SHA-256: 42f7712782a03b5f86ead435d50523a427326aaf4e1957f9f7b827d7bdd71589 xorg-x11-server-Xvfb-debuginfo-1.20.11-20.el9_2.ppc64le.rpm SHA-256: 9e3ccacc0636998bae3a325575ff82c281f972b6819ae5a2411477db79505824 xorg-x11-server-common-1.20.11-20.el9_2.ppc64le.rpm SHA-256: 7aba530b19d031224289cf6e9f3a24adb203943a6671b776e66a7fdb0fdf6b1d xorg-x11-server-debuginfo-1.20.11-20.el9_2.ppc64le.rpm SHA-256: ea2d63ff3cdfbc55955366208fa531a27353aefe86987ba366d41277b8cbf08a xorg-x11-server-debugsource-1.20.11-20.el9_2.ppc64le.rpm SHA-256: 443bc9849d4429a47e022ed90e64441e52c1bb75c3b6d4f5ec024bd517be6abb Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.2 SRPM xorg-x11-server-1.20.11-20.el9_2.src.rpm SHA-256: d9be5b53bf270256204278f0338babbd00760d61d7b6ca9ec8ed281535556f76 x86_64 xorg-x11-server-Xdmx-1.20.11-20.el9_2.x86_64.rpm SHA-256: f1dddbe39de5d3ce39cd6bd98b93525f2db8bc1ea2b03fc5445bc61cddf3041d xorg-x11-server-Xdmx-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: 448b675762b3887ebeb855c5e238bbffc63594ec5a1dd3198a9105b90a234efe xorg-x11-server-Xephyr-1.20.11-20.el9_2.x86_64.rpm SHA-256: 4e78505558e1ba30c567aaabd7eab379af2408f8d3e8400e2f482ea6308b82e5 xorg-x11-server-Xephyr-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: 83f356f1223e8f9cbbf8fd35342c24e4f2b870d9ec9792ef524365a2c2fb07a4 xorg-x11-server-Xnest-1.20.11-20.el9_2.x86_64.rpm SHA-256: 9faf4b90616ccd1e436f58eac3f400e50979b9749bebf14b8037e80402ad9b62 xorg-x11-server-Xnest-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: d042cc38fc5a0db3913e7c3b49d6acec3613d3e07927dd114d2ae9d3122e724d xorg-x11-server-Xorg-1.20.11-20.el9_2.x86_64.rpm SHA-256: 87c6e507ab03bfce1447ac468c788fbc8211fecfcf0f4671fb917353d23eef0e xorg-x11-server-Xorg-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: 4f3cfa20c6db302aeb380b9581a77a1e80352395557cb6ecaef5c0d657dff226 xorg-x11-server-Xvfb-1.20.11-20.el9_2.x86_64.rpm SHA-256: 19140d8b7e4ed7d1026795c20e07910f8883a4bfc32eb38ef56d894ec3b3f526 xorg-x11-server-Xvfb-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: c788537b154131e0d07ff7fa11b7da4666c8ae1579664937a4c5ad46c88f9a8c xorg-x11-server-common-1.20.11-20.el9_2.x86_64.rpm SHA-256: 19e9cbc1ac5fd2a41ba31768f0a5b7caf95c43ee471e2d46b42d09ce531c1c81 xorg-x11-server-debuginfo-1.20.11-20.el9_2.x86_64.rpm SHA-256: 6025b9161a45207022c54da569af9ab05d612b5ee269cb520b7896a5d42bab1b xorg-x11-server-debugsource-1.20.11-20.el9_2.x86_64.rpm SHA-256: ea946e3b6e462c2947f109bb7afe01c3409ad1fb7ec431bd469d1756d8126568 Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.2 SRPM xorg-x11-server-1.20.11-20.el9_2.src.rpm SHA-256: d9be5b53bf270256204278f0338babbd00760d61d7b6ca9ec8ed281535556f76 aarch64 xorg-x11-server-Xdmx-1.20.11-20.el9_2.aarch64.rpm SHA-256: 9b06c6fdea104d114c0355e0dc488297a44ebc16b857d4a685df62630698afee xorg-x11-server-Xdmx-debuginfo-1.20.11-20.el9_2.aarch64.rpm SHA-256: e2c0161e385399c1011a20fedbc0b721fa2b304e42b5e59ee17310e567cc5f2f xorg-x11-server-Xephyr-1.20.11-20.el9_2.aarch64.rpm SHA-256: a9f255cc18650213c36ec93390bb578d690e18cc3d62c36a26edee2993456042 xorg-x11-server-Xephyr-debuginfo-1.20.11-20.el9_2.aarch64.rpm SHA-256: 63dcee42c31c9b55fb9dc569b5caf3453eaea3eea8eb0046fddb486b9b929760 xorg-x11-server-Xnest-1.