EUVD-2026-56344
GHSA-6wgm-2w24-7r22
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local-only race condition (AV:L, AC:H) requires an existing low-privilege account (PR:L); successful exploitation yields full SYSTEM access (C:H/I:H/A:H) with no scope change beyond the compromised host.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Push Notifications allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in Windows Push Notifications exposes a broad range of Microsoft Windows desktop and server editions to full SYSTEM-level compromise by an authenticated low-privileged local attacker. The flaw is a race condition (CWE-362) in which concurrent threads access a shared resource without adequate synchronization, creating a timing window that can be manipulated to corrupt execution state and redirect control to a privileged context. Microsoft has confirmed the issue and released patches across all affected Windows build lines; no public exploit code or CISA KEV listing has been identified at time of analysis.
Technical ContextAI
The vulnerability resides in Windows Push Notifications, a core Windows subsystem that brokers delivery of application and system notifications. CWE-362 (Concurrent Execution Using Shared Resource with Improper Synchronization) is the root cause class: two or more threads compete over a shared resource without sufficient locking or memory-ordering guarantees, producing a time-of-check-to-time-of-use (TOCTOU) window. The CVSS vector AV:L/AC:H confirms the attack is strictly local and requires winning a precise timing race, consistent with classic thread-scheduling exploits. Affected product families span Windows 10 (builds 17763 through 19045), Windows 11 (builds 22631 through 28000), Windows Server 2019 (build 17763), Windows Server 2022 (build 20348), and Windows Server 2025 (build 26100), as catalogued under EUVD-2026-56344. The Push Notifications subsystem is present and active by default in all listed editions, requiring no special configuration to be exposed.
RemediationAI
Microsoft has released cumulative updates resolving this vulnerability for all affected Windows editions, distributed via Windows Update, Windows Server Update Services, and the Microsoft Update Catalog; the full advisory is at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62690. Administrators should ensure each affected system is updated to at least the following build thresholds: Windows 10 1809 and Windows Server 2019 to 10.0.17763.9115; Windows 10 21H2 to 10.0.19044.7663; Windows 10 22H2 to 10.0.19045.7663; Windows Server 2022 to 10.0.20348.5499; Windows 11 23H2 to 10.0.22631.7517; Windows 11 24H2 to 10.0.26100.9168; Windows Server 2025 to 10.0.26100.33296; Windows 11 25H2 to 10.0.26200.9168; and Windows 11 26H1 to 10.0.28000.2704. Where immediate patching is not feasible, reduce the pool of users who can obtain interactive or remote desktop logon rights on the affected system, which limits who can be in a position to trigger the race condition locally - note this is a partial risk reduction, not a remediation, and does not protect against attackers who already hold a low-privileged session via malware or lateral movement.
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External POC / Exploit Code
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