EUVD-2026-43800
GHSA-g9cg-444v-4rf9
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local authenticated foothold gives AV:L/PR:L; winning the timing race gives AC:H; successful elevation yields full host C:H/I:H/A:H with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Clipboard Server allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Clipboard Server (Windows 10 1809 through Windows 11 26H1 and Windows Server 2019 through 2025) allows an already-authenticated low-privileged user to win a race condition and gain higher privileges on the host. Microsoft credits its own researchers and has shipped a fix; there is no public exploit identified at time of analysis and the CVSS base score is 7.0 (High). The high attack complexity reflects the timing precision needed to exploit the race, which meaningfully limits reliable weaponization.
Technical ContextAI
The flaw is a CWE-362 concurrent-execution-with-shared-resource race condition ('improper synchronization') in the Windows Clipboard Server, the OS component that brokers clipboard data between processes and sessions. Because clipboard operations run in a shared, privileged service context, unsynchronized access to a shared resource creates a window in which an attacker-controlled operation can interleave with a privileged one, leading to a state corruption an attacker can leverage for elevation. The CPE data confirms the defect lives in the base OS across the modern Windows client and server line (Windows 10 1809/21H2/22H2, Windows 11 24H2/25H2/26H1, Windows Server 2019/2022/2025 including Server Core), indicating a shared underlying Clipboard Server code path rather than an application-specific bug.
RemediationAI
Patch available per vendor advisory: apply the Microsoft security update for CVE-2026-49183 for your specific Windows or Windows Server release via Windows Update / WSUS / the MSRC Update Guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49183, which lists the exact fixed build per SKU. No standalone workaround is published for this Clipboard Server race condition; because exploitation requires an authenticated local foothold, the practical compensating controls are to enforce least privilege and restrict interactive/local logon so low-privileged and untrusted users cannot run code on sensitive hosts, and to monitor for unexpected privilege changes - these reduce the attacker population but do not close the underlying race, so patching remains the only complete fix.
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Same weakness CWE-362 – Race Condition
View allSame technique Information Disclosure
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External POC / Exploit Code
Leaving vuln.today