Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local access with an existing low-privileged account (AV:L/PR:L), a non-deterministic race window drives AC:H, and privilege elevation yields full C:H/I:H/A:H with unchanged scope.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Runtime allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Runtime (WinRT) component of Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025 allows an authenticated local attacker to win a race condition and gain higher privileges. The flaw stems from improper synchronization of a shared resource (CWE-362); successful exploitation yields high confidentiality, integrity, and availability impact. No public exploit is identified at time of analysis, and it is not listed in CISA KEV; Microsoft has released a patch.
Technical ContextAI
Windows Runtime (WinRT) is the object-oriented API layer that underpins modern Windows applications and system services across the OS. The root cause is CWE-362, a race condition arising from concurrent execution over a shared resource without proper synchronization: two or more threads access the same object during a narrow timing window, letting an attacker manipulate state between a check and its use (TOCTOU-style). Per the CPE data the flaw is present in the application layer of Windows 11 Version 24H2, 25H2, and 26H1, plus Windows Server 2025 including the Server Core installation, indicating a shared code path in the current Windows servicing branch rather than a legacy-only defect.
RemediationAI
Patch available per vendor advisory - apply the Microsoft security update for CVE-2026-50345 to all affected Windows 11 24H2/25H2/26H1 and Windows Server 2025 (including Server Core) systems via the monthly cumulative update; the fixed build numbers are listed in the MSRC guidance at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50345. No standalone workaround is documented in the provided data, and because the vulnerability requires prior local low-privileged access, the practical compensating controls until patching are to reduce the population of local users who could stage the attack: enforce least privilege, restrict interactive and remote-desktop logon rights on servers, and prioritize patching multi-user and shared hosts (RDS/session hosts) where untrusted low-privileged accounts run code, since those most directly satisfy the PR:L precondition.
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Same weakness CWE-362 – Race Condition
View allSame technique Race Condition
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-43895
GHSA-mfrp-f2w3-cjvx