Red Hat Product Errata RHSA-2026:26610 - Security Advisory Issued: 2026-06-17 Updated: 2026-06-17 RHSA-2026:26610 - Security Advisory Overview Updated Packages Synopsis Important: xorg-x11-server 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 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 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-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): [xserver] Backport other security fixes without a CVE assigned [rhel-9.8.z] (JIRA:RHEL-184288) 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-1.20.11-34.el9_8.2.src.rpm SHA-256: 740561211130c4c98d8884d2d0555dcb41d6203d6ddc4e947e386d7fc80992a6 x86_64 xorg-x11-server-Xdmx-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 837969bb5dfc1fb3b9743538ea74ca99d73593769c80433e61a14bfbca9b3019 xorg-x11-server-Xdmx-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 0c0c1b809bfa47d1978c56bba060e9569845ee670c6dac900b3fcabc253f70dc xorg-x11-server-Xephyr-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 0bec570ae37c38fb0982c8b9de98df3b9a1d4afc22343abf4270c4295b1ab5eb xorg-x11-server-Xephyr-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: ab0d2c1f4919bffc880fc34b8825c737cbcd2d6670a69690eba3e5e2754cdae7 xorg-x11-server-Xnest-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: fe0b29981779fb481da8a162b767f91cdf976230d6fd15851abe04245b1196de xorg-x11-server-Xnest-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 1103dde991bb6b06e1934bdcfb34c79a79ba39cc6c3db6077b987ed58e0e6009 xorg-x11-server-Xorg-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: f4fdd91a18545fd645b3c84da4cea681f26e25950e9650ab174f2c4c6eca3a16 xorg-x11-server-Xorg-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 00af5ad7ca18d2a5e7b55c73c0a7d98c7f7bbd7ae11a6487481c76b66bd6a7ea xorg-x11-server-Xvfb-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 9e9628aeeae5d495eeb5c6aacd6b60b723c6fdd3929ac59cb6d21a5653f13256 xorg-x11-server-Xvfb-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: b4edcc70c55096fab1aa415cd77f8a5d9ce7080a7a0f5b3f4b62b1a02346b4b5 xorg-x11-server-common-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: cd1a57f3d284e13f152d2e69ae141590711f154b7a269352c7877a16a8588430 xorg-x11-server-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 4453551e55ef708a8a4040944654fe3552233fd2cedf64d24c305b21db072109 xorg-x11-server-debugsource-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: db5e7ee210faa56583d3285a373dfee65338ccbcfe34439420aa13cf495d545e Red Hat Enterprise Linux for x86_64 - Extended Update Support 9.8 SRPM xorg-x11-server-1.20.11-34.el9_8.2.src.rpm SHA-256: 740561211130c4c98d8884d2d0555dcb41d6203d6ddc4e947e386d7fc80992a6 x86_64 xorg-x11-server-Xdmx-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 837969bb5dfc1fb3b9743538ea74ca99d73593769c80433e61a14bfbca9b3019 xorg-x11-server-Xdmx-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 0c0c1b809bfa47d1978c56bba060e9569845ee670c6dac900b3fcabc253f70dc xorg-x11-server-Xephyr-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 0bec570ae37c38fb0982c8b9de98df3b9a1d4afc22343abf4270c4295b1ab5eb xorg-x11-server-Xephyr-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: ab0d2c1f4919bffc880fc34b8825c737cbcd2d6670a69690eba3e5e2754cdae7 xorg-x11-server-Xnest-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: fe0b29981779fb481da8a162b767f91cdf976230d6fd15851abe04245b1196de xorg-x11-server-Xnest-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 1103dde991bb6b06e1934bdcfb34c79a79ba39cc6c3db6077b987ed58e0e6009 xorg-x11-server-Xorg-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: f4fdd91a18545fd645b3c84da4cea681f26e25950e9650ab174f2c4c6eca3a16 xorg-x11-server-Xorg-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 00af5ad7ca18d2a5e7b55c73c0a7d98c7f7bbd7ae11a6487481c76b66bd6a7ea xorg-x11-server-Xvfb-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 9e9628aeeae5d495eeb5c6aacd6b60b723c6fdd3929ac59cb6d21a5653f13256 xorg-x11-server-Xvfb-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: b4edcc70c55096fab1aa415cd77f8a5d9ce7080a7a0f5b3f4b62b1a02346b4b5 xorg-x11-server-common-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: cd1a57f3d284e13f152d2e69ae141590711f154b7a269352c7877a16a8588430 xorg-x11-server-debuginfo-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: 4453551e55ef708a8a4040944654fe3552233fd2cedf64d24c305b21db072109 xorg-x11-server-debugsource-1.20.11-34.el9_8.2.x86_64.rpm SHA-256: db5e7ee210faa56583d3285a373dfee65338ccbcfe34439420aa13cf495d545e Red Hat Enterprise Linux for IBM z Systems 9 SRPM xorg-x11-server-1.20.11-34.el9_8.2.src.rpm SHA-256: 740561211130c4c98d8884d2d0555dcb41d6203d6ddc4e947e386d7fc80992a6 s390x xorg-x11-server-Xdmx-1.20.11-34.el9_8.2.s390x.rpm SHA-256: