Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Primary rating from Vendor (redhat).
CVSS VectorVendor: redhat
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.
AnalysisAI
Local privilege escalation in X.Org X server and Xwayland enables authenticated local users to trigger a use-after-free in miSyncDestroyFence() by racing two client connections against a shared fence object. Successful exploitation can crash the display server or escalate privileges to root when the X server runs as root, which remains common on legacy and embedded Linux deployments. No public exploit identified at time of analysis, but an upstream fix has been committed by the X.Org maintainers.
Technical ContextAI
The vulnerability resides in the MIT-SHM/Sync extension code path of the X.Org xserver, specifically miSyncDestroyFence() within the miSync fence-handling logic shared between native X11 and the Xwayland compatibility server. The root cause is CWE-416 (Use After Free): the fence object's lifetime is not correctly serialized between the client that awaits the fence trigger and a separate client that destroys it, leaving a dangling function pointer that is later invoked when the trigger fires. Because the Sync extension exposes fence primitives over the X protocol, any local client with a session connection to the display server can manipulate these objects. The affected components are shipped as part of Red Hat Enterprise Linux 6 through 10 per the provided CPEs, and the upstream patch is tracked at gitlab.freedesktop.org commit f5abfb6.
RemediationAI
Apply the upstream fix at commit f5abfb61994471023d8c6470428c8e30c411cc0b from https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b once your distribution publishes a tagged release containing it; for Red Hat customers, monitor https://access.redhat.com/security/cve/CVE-2026-50257 and Bugzilla 2485382 for RHSA errata across RHEL 6 through 10 and install the updated xorg-x11-server and xwayland packages. Upstream fix available (commit); a tagged released patched xserver version is not independently confirmed in the provided data, so verify against the X.Org announce list (https://lists.x.org/archives/xorg-announce/2026-June/003702.html) for the corresponding 21.1.x point release. As compensating controls until patches land, run Xorg rootless (already default on modern Fedora/RHEL via systemd-logind seat takeover) to neutralize the privilege-escalation path while still leaving denial of service possible, prefer pure Wayland sessions where Xwayland runs as the unprivileged user, and on multi-user hosts restrict shell access since the attacker must connect to the local X server - note that disabling the SYNC extension entirely will break compositors and many GTK/Qt applications, so it is not a practical mitigation.
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Same weakness CWE-416 – Use After Free
View allSame technique Use After Free
View allVendor StatusVendor
SUSE
Severity: Important| Product | Status |
|---|---|
| SUSE Linux Enterprise Desktop 15 SP7 | Affected |
| SUSE Linux Enterprise Desktop 15 SP7 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | Affected |
| SUSE Linux Enterprise Server 15 SP7 | Affected |
| SUSE Linux Enterprise Server 15 SP7 | Affected |
| SUSE Linux Enterprise Server 16.0 | Affected |
| SUSE Linux Enterprise Server 16.1 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.0 | Affected |
| SUSE Linux Enterprise Server for SAP applications 16.1 | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | Affected |
| openSUSE Leap 16.0 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP4 | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP5 | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP6 | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP4 | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP5 | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | Affected |
| SUSE Linux Enterprise Server 12 SP5 | Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS | Affected |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | Affected |
| SUSE Linux Enterprise Server 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP6 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP6-LTSS | Affected |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP5 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | Affected |
| SUSE Manager Proxy 4.3 | Affected |
| SUSE Manager Proxy LTS 4.3 | Affected |
| SUSE Manager Retail Branch Server 4.3 | Affected |
| SUSE Manager Retail Branch Server LTS 4.3 | Affected |
| SUSE Manager Server 4.3 | Affected |
| SUSE Manager Server LTS 4.3 | Affected |
| SUSE CaaS Platform 4.0 | Not-Affected |
| SUSE Enterprise Storage 6 | Not-Affected |
| SUSE Enterprise Storage 7 | Not-Affected |
| SUSE Enterprise Storage 7.1 | Not-Affected |
| SUSE Linux Enterprise Desktop 12 SP2 | Affected |
| SUSE Linux Enterprise Desktop 12 SP3 | Affected |
| SUSE Linux Enterprise Desktop 12 SP4 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Desktop 15 SP6 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Point of Sale 12 SP2-CLIENT | Affected |
| SUSE Linux Enterprise Real Time 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Real Time 15 SP4 | Affected |
| SUSE Linux Enterprise Server 12 SP2 | Affected |
| SUSE Linux Enterprise Server 12 SP2-BCL | Affected |
| SUSE Linux Enterprise Server 12 SP2-ESPOS | Affected |
| SUSE Linux Enterprise Server 12 SP2-LTSS | Affected |
| SUSE Linux Enterprise Server 12 SP3 | Affected |
| SUSE Linux Enterprise Server 12 SP3-BCL | Affected |
| SUSE Linux Enterprise Server 12 SP3-ESPOS | Affected |
| SUSE Linux Enterprise Server 12 SP3-LTSS | Affected |
| SUSE Linux Enterprise Server 12 SP4 | Not-Affected |
| SUSE Linux Enterprise Server 12 SP4-ESPOS | Not-Affected |
| SUSE Linux Enterprise Server 12 SP4-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3-BCL | Not-Affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | Not-Affected |
| SUSE Linux Enterprise Server for Raspberry Pi 12 SP2 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP2 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP3 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 12 SP4 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP2 | Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP3 | Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP4 | Not-Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP5 | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP1 | Not-Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP2 | Not-Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP3 | Not-Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP4 | Not-Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP5 | Not-Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP6 | Not-Affected |
| SUSE Manager Proxy 4.0 | Not-Affected |
| SUSE Manager Proxy 4.1 | Not-Affected |
| SUSE Manager Proxy 4.2 | Not-Affected |
| SUSE Manager Retail Branch Server 4.0 | Not-Affected |
| SUSE Manager Retail Branch Server 4.1 | Not-Affected |
| SUSE Manager Retail Branch Server 4.2 | Not-Affected |
| SUSE Manager Server 4.0 | Not-Affected |
| SUSE Manager Server 4.1 | Not-Affected |
| SUSE Manager Server 4.2 | Not-Affected |
| SUSE OpenStack Cloud 7 | Affected |
| SUSE OpenStack Cloud 8 | Affected |
| SUSE OpenStack Cloud 9 | Not-Affected |
| SUSE OpenStack Cloud Crowbar 8 | Affected |
| SUSE OpenStack Cloud Crowbar 9 | Not-Affected |
| openSUSE Leap 15.3 | Not-Affected |
| openSUSE Leap 15.4 | Affected |
| openSUSE Leap 15.5 | Affected |
| openSUSE Leap 15.6 | Affected |
| SUSE Manager Proxy 4.3 LTS | Affected |
| SUSE Manager Retail Branch Server 4.3 LTS | Affected |
| SUSE Manager Server 4.3 LTS | Affected |
| suse/kiosk/xorg:21 | Affected |
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-34812
GHSA-5p7p-jgvj-4v95