Red Hat Product Errata RHSA-2026:26590 - Security Advisory Issued: 2026-06-17 Updated: 2026-06-17 RHSA-2026:26590 - Security Advisory Overview Updated Packages Synopsis Important: xorg-x11-server-Xwayland security, bug fix, and enhancement 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-Xwayland is now available for Red Hat Enterprise Linux 9. 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 Xwayland is an X server for running X clients under Wayland. Security Fix(es): xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libXfont2 name length mismatch (CVE-2026-50256) xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in miSyncDestroyFence() (CVE-2026-50257) xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in XKB key types due to unchecked shift levels (CVE-2026-50258) xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in XKB SetMap request via mapWidths indexing (CVE-2026-50259) xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in FreeCounter() (CVE-2026-50260) xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in SyncChangeCounter() (CVE-2026-50261) xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: out-of-bounds read/write in GLX ChangeDrawableAttributes (CVE-2026-50262) xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free information disclosure in CreateSaverWindow() (CVE-2026-50263) xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: out-of-bounds heap write in DRI2 DRIGetBuffers/DRIGetBuffersWithFormat (CVE-2026-50264) Bug Fix(es) and Enhancement(s): [xwayland] Backport other security fixes without a CVE assigned [rhel-9.8.z] (JIRA:RHEL-184292) 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 9 x86_64 Red Hat Enterprise Linux for x86_64 - Extended Update Support 9.8 x86_64 Red Hat Enterprise Linux for IBM z Systems 9 s390x Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.8 s390x Red Hat Enterprise Linux for Power, little endian 9 ppc64le Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.8 ppc64le Red Hat Enterprise Linux for ARM 64 9 aarch64 Red Hat Enterprise Linux for ARM 64 - Extended Update Support 9.8 aarch64 Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions 9.8 ppc64le Red Hat Enterprise Linux for x86_64 - Update Services for SAP Solutions 9.8 x86_64 Red Hat CodeReady Linux Builder for x86_64 9 x86_64 Red Hat CodeReady Linux Builder for Power, little endian 9 ppc64le Red Hat CodeReady Linux Builder for ARM 64 9 aarch64 Red Hat CodeReady Linux Builder for IBM z Systems 9 s390x Red Hat CodeReady Linux Builder for x86_64 - Extended Update Support 9.8 x86_64 Red Hat CodeReady Linux Builder for Power, little endian - Extended Update Support 9.8 ppc64le Red Hat CodeReady Linux Builder for IBM z Systems - Extended Update Support 9.8 s390x Red Hat CodeReady Linux Builder for ARM 64 - Extended Update Support 9.8 aarch64 Red Hat Enterprise Linux for ARM 64 - 4 years of updates 9.8 aarch64 Red Hat Enterprise Linux for IBM z Systems - 4 years of updates 9.8 s390x Red Hat Enterprise Linux for x86_64 - Extended Life Cycle 9.8 x86_64 Red Hat Enterprise Linux for ARM 64 - Extended Life Cycle 9.8 aarch64 Red Hat Enterprise Linux for Power, little endian - Extended Life Cycle 9.8 ppc64le Red Hat Enterprise Linux for IBM z Systems - Extended Life Cycle 9.8 s390x Fixes BZ - 2485380 - CVE-2026-50256 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in font alias resolution due to libXfont2 name length mismatch BZ - 2485382 - CVE-2026-50257 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in miSyncDestroyFence() BZ - 2485383 - CVE-2026-50258 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in XKB key types due to unchecked shift levels BZ - 2485384 - CVE-2026-50259 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: stack buffer overflow in XKB SetMap request via mapWidths indexing BZ - 2485385 - CVE-2026-50260 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in FreeCounter() BZ - 2485386 - CVE-2026-50261 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free in SyncChangeCounter() BZ - 2485387 - CVE-2026-50262 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: out-of-bounds read/write in GLX ChangeDrawableAttributes BZ - 2485388 - CVE-2026-50263 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: use-after-free information disclosure in CreateSaverWindow() BZ - 2485389 - CVE-2026-50264 xorg-x11-server: xorg-x11-server-Xwayland: xorg-x11-server: out-of-bounds heap write in DRI2 DRIGetBuffers/DRIGetBuffersWithFormat CVEs CVE-2026-50256 CVE-2026-50257 CVE-2026-50258 CVE-2026-50259 CVE-2026-50260 CVE-2026-50261 CVE-2026-50262 CVE-2026-50263 CVE-2026-50264 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 9 SRPM xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.src.rpm SHA-256: fbc468980f0989b246e2cdaad3f7fc730765d2036d54e4156df550249206ddcc x86_64 xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.x86_64.rpm SHA-256: d90a19f56ea786546bb94709450265192c46a3b7594d9f675f40f71f3cf96696 xorg-x11-server-Xwayland-debuginfo-24.1.9-4.el9_8.2.x86_64.rpm SHA-256: 4450f4209266cffe99077a8a80655da4eb2b087583ca516391c52610960a82ea xorg-x11-server-Xwayland-debugsource-24.1.9-4.el9_8.2.x86_64.rpm SHA-256: 6587283f88e47d4b39b74013042b5c438ea981f9536b8d9e787969a269e707b7 Red Hat Enterprise Linux for x86_64 - Extended Update Support 9.8 SRPM xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.src.rpm SHA-256: fbc468980f0989b246e2cdaad3f7fc730765d2036d54e4156df550249206ddcc x86_64 xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.x86_64.rpm SHA-256: d90a19f56ea786546bb94709450265192c46a3b7594d9f675f40f71f3cf96696 xorg-x11-server-Xwayland-debuginfo-24.1.9-4.el9_8.2.x86_64.rpm SHA-256: 4450f4209266cffe99077a8a80655da4eb2b087583ca516391c52610960a82ea xorg-x11-server-Xwayland-debugsource-24.1.9-4.el9_8.2.x86_64.rpm SHA-256: 6587283f88e47d4b39b74013042b5c438ea981f9536b8d9e787969a269e707b7 Red Hat Enterprise Linux for IBM z Systems 9 SRPM xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.src.rpm SHA-256: fbc468980f0989b246e2cdaad3f7fc730765d2036d54e4156df550249206ddcc s390x xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.s390x.rpm SHA-256: 2fbb30240de2b96cbf1cd6b7b1214a69d4670937129fb1e28286caee890c2afc xorg-x11-server-Xwayland-debuginfo-24.1.9-4.el9_8.2.s390x.rpm SHA-256: 749c4ca5ed3b1406f1a73c1cf6ce7fb0e0493318af34d0d367c060e90cc13e3d xorg-x11-server-Xwayland-debugsource-24.1.9-4.el9_8.2.s390x.rpm SHA-256: b9fe77169736dce8e73f11948385664869a4759178e9c7d179717fa8e9050352 Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 9.8 SRPM xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.src.rpm SHA-256: fbc468980f0989b246e2cdaad3f7fc730765d2036d54e4156df550249206ddcc s390x xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.s390x.rpm SHA-256: 2fbb30240de2b96cbf1cd6b7b1214a69d4670937129fb1e28286caee890c2afc xorg-x11-server-Xwayland-debuginfo-24.1.9-4.el9_8.2.s390x.rpm SHA-256: 749c4ca5ed3b1406f1a73c1cf6ce7fb0e0493318af34d0d367c060e90cc13e3d xorg-x11-server-Xwayland-debugsource-24.1.9-4.el9_8.2.s390x.rpm SHA-256: b9fe77169736dce8e73f11948385664869a4759178e9c7d179717fa8e9050352 Red Hat Enterprise Linux for Power, little endian 9 SRPM xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.src.rpm SHA-256: fbc468980f0989b246e2cdaad3f7fc730765d2036d54e4156df550249206ddcc ppc64le xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.ppc64le.rpm SHA-256: 4e383cba1fb77cab2f4f7bc9bba024cbb3b1e30e0292f4bdb9dd2c0f1a5ecf0b xorg-x11-server-Xwayland-debuginfo-24.1.9-4.el9_8.2.ppc64le.rpm SHA-256: 9c1b71725415e061e217dcac65e5231ba8b05fab6d05c0bb595902bcb9072736 xorg-x11-server-Xwayland-debugsource-24.1.9-4.el9_8.2.ppc64le.rpm SHA-256: 304302adb3e4a8f152aeec0d448868008b8841a02efd37289646068e4574b112 Red Hat Enterprise Linux for Power, little endian - Extended Update Support 9.8 SRPM xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.src.rpm SHA-256: fbc468980f0989b246e2cdaad3f7fc730765d2036d54e4156df550249206ddcc ppc64le xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.ppc64le.rpm SHA-256: 4e383cba1fb77cab2f4f7bc9bba024cbb3b1e30e0292f4bdb9dd2c0f1a5ecf0b xorg-x11-server-Xwayland-debuginfo-24.1.9-4.el9_8.2.ppc64le.rpm SHA-256: 9c1b71725415e061e217dcac65e5231ba8b05fab6d05c0bb595902bcb9072736 xorg-x11-server-Xwayland-debugsource-24.1.9-4.el9_8.2.ppc64le.rpm SHA-256: 304302adb3e4a8f152aeec0d448868008b8841a02efd37289646068e4574b112 Red Hat Enterprise Linux for ARM 64 9 SRPM xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.src.rpm SHA-256: fbc468980f0989b246e2cdaad3f7fc730765d2036d54e4156df550249206ddcc aarch64 xorg-x11-server-Xwayland-24.1.9-4.el9_8.2.aarch64.rpm SHA-256: e7b3cac58c67885ffaf578936bae1453d96ebca4fa2a20e9f021c65ac624e2f9 xorg-x11-server-Xwayland-debuginfo-24.1.9-4.el9_8.2.aarch64.rpm SHA-256: 9ebf52b0838a3395ab3ffeb740aa4cd0bc8fb87e8435259e2574a499e8e0e87b xorg-x11-server-Xwayland-debugsource-24.1.9-4.e