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 FreeCounter(). A client that sets up multiple SyncCounters and awaits on those triggers can trigger a use-after-free when destroying those counters via a second client connection. This may be used to crash the server, or for privilege escalation if the X server runs as root.
AnalysisAI
Local privilege escalation in the X.Org X server and Xwayland arises from a use-after-free in FreeCounter() when SyncCounter objects are destroyed across multiple client connections. Authenticated local attackers on affected Red Hat Enterprise Linux 6 through 10 systems can crash the server or escalate to root when the X server runs with elevated privileges. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV.
Technical ContextAI
The vulnerability resides in the XSync extension of the X.Org X server (xserver) and its Wayland-compatibility component Xwayland, both maintained at gitlab.freedesktop.org/xorg/xserver. SyncCounters are server-side objects exposed by the XSync protocol extension that allow clients to coordinate timing via shared counter values and triggers (alarms). The root cause is CWE-416 (Use-After-Free): when one client allocates multiple SyncCounters with pending triggers and a second client connection causes FreeCounter() to release those counters, dangling references to the freed counter memory remain reachable, allowing subsequent operations to dereference or write to freed heap memory. Exploitation primitives from use-after-free in C-based servers like xserver typically allow attacker-controlled function pointer overwrite or heap layout manipulation leading to arbitrary code execution.
RemediationAI
Upstream fix available (commit f5abfb61994471023d8c6470428c8e30c411cc0b at https://gitlab.freedesktop.org/xorg/xserver/-/commit/f5abfb61994471023d8c6470428c8e30c411cc0b); a released patched version was not independently confirmed in the supplied data, so administrators should apply Red Hat errata referenced from https://access.redhat.com/security/cve/CVE-2026-50260 once they list specific xorg-x11-server and xorg-x11-server-Xwayland package versions. As compensating controls until patched packages are deployed, prefer Wayland sessions where Xwayland runs unprivileged rather than legacy Xorg-as-root sessions (trade-off: legacy X11-only apps requiring root X features may break), restrict local interactive logins on multi-user systems via PAM/access.conf to reduce the pool of authenticated attackers (trade-off: operational friction), and where possible disable the XSync extension or block untrusted clients from connecting to the server socket using xhost/Xauthority hardening (trade-off: applications relying on XSync alarms such as some compositors and animation toolkits will degrade or fail).
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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 | Affected |
| SUSE Linux Enterprise Server 15 SP4-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP5 | Affected |
| SUSE Linux Enterprise Server 15 SP5-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP6 | 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 | Affected |
| SUSE Enterprise Storage 6 | Affected |
| SUSE Enterprise Storage 7 | Affected |
| SUSE Enterprise Storage 7.1 | Affected |
| SUSE Linux Enterprise Desktop 12 SP2 | Affected |
| SUSE Linux Enterprise Desktop 12 SP3 | Affected |
| SUSE Linux Enterprise Desktop 12 SP4 | Affected |
| SUSE Linux Enterprise Desktop 15 SP1 | Affected |
| SUSE Linux Enterprise Desktop 15 SP2 | Affected |
| SUSE Linux Enterprise Desktop 15 SP3 | Affected |
| SUSE Linux Enterprise Desktop 15 SP4 | Affected |
| SUSE Linux Enterprise Desktop 15 SP5 | Affected |
| SUSE Linux Enterprise Desktop 15 SP6 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | Affected |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | 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 | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP2 | Affected |
| SUSE Linux Enterprise Module for Basesystem 15 SP3 | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP1 | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | Affected |
| SUSE Linux Enterprise Module for Development Tools 15 SP3 | Affected |
| SUSE Linux Enterprise Point of Sale 12 SP2-CLIENT | Affected |
| SUSE Linux Enterprise Real Time 15 SP2 | Affected |
| SUSE Linux Enterprise Real Time 15 SP3 | 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 | Affected |
| SUSE Linux Enterprise Server 12 SP4-ESPOS | Affected |
| SUSE Linux Enterprise Server 12 SP4-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP1 | Affected |
| SUSE Linux Enterprise Server 15 SP1-BCL | Affected |
| SUSE Linux Enterprise Server 15 SP1-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP2 | Affected |
| SUSE Linux Enterprise Server 15 SP2-BCL | Affected |
| SUSE Linux Enterprise Server 15 SP2-LTSS | Affected |
| SUSE Linux Enterprise Server 15 SP3 | Affected |
| SUSE Linux Enterprise Server 15 SP3-BCL | Affected |
| SUSE Linux Enterprise Server 15 SP3-LTSS | 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 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | Affected |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | 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 | Affected |
| SUSE Linux Enterprise Software Development Kit 12 SP5 | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP1 | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP2 | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP3 | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP4 | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP5 | Affected |
| SUSE Linux Enterprise Workstation Extension 15 SP6 | Affected |
| SUSE Manager Proxy 4.0 | Affected |
| SUSE Manager Proxy 4.1 | Affected |
| SUSE Manager Proxy 4.2 | Affected |
| SUSE Manager Retail Branch Server 4.0 | Affected |
| SUSE Manager Retail Branch Server 4.1 | Affected |
| SUSE Manager Retail Branch Server 4.2 | Affected |
| SUSE Manager Server 4.0 | Affected |
| SUSE Manager Server 4.1 | Affected |
| SUSE Manager Server 4.2 | Affected |
| SUSE OpenStack Cloud 7 | Affected |
| SUSE OpenStack Cloud 8 | Affected |
| SUSE OpenStack Cloud 9 | Affected |
| SUSE OpenStack Cloud Crowbar 8 | Affected |
| SUSE OpenStack Cloud Crowbar 9 | Affected |
| openSUSE Leap 15.3 | 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-2026-34816
GHSA-7j37-rf7v-jf5c