EUVD-2026-43841
GHSA-85p7-8497-7788
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local, authenticated low-priv attacker (AV:L/PR:L) exploiting a timing-dependent race (AC:H) with no user interaction to gain privileges yielding full C/I/A impact.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Clip Service allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Clip Service (clipboard/cloud clipboard component, cbdhsvc) affects a broad range of Windows 10, Windows 11, and Windows Server 2019-2025 builds, where a race condition in concurrent access to a shared resource lets an already-authenticated local attacker win a timing window to gain higher privileges. Reported by Microsoft with a patch available; there is no public exploit identified at time of analysis and it is not listed in CISA KEV. Note a source conflict: the description and CWE describe privilege elevation with high confidentiality/integrity/availability impact, while the intelligence tags label it 'Information Disclosure' - treat the primary impact as local EoP per the CVSS vector.
Technical ContextAI
The affected component is the Windows Clip Service (cbdhsvc), the service backing clipboard history and cloud clipboard synchronization on modern Windows. The root cause is CWE-362, concurrent execution using a shared resource with improper synchronization (a race condition): two or more threads/processes access shared state without adequate locking, so an attacker who can interleave operations at the right moment can manipulate that state during the unsynchronized window. Because the Clip Service runs with elevated system privileges while exposing functionality to lower-privileged user sessions, winning the race can allow a low-privileged process to influence a privileged operation and escalate. The CPE data confirms the affected surface is the OS-bundled service across Windows 10 (1809, 21H2, 22H2), Windows 11 (24H2, 25H2, 26H1), and Windows Server 2019, 2022, and 2025 including Server Core installations.
RemediationAI
Apply the Microsoft security update for CVE-2026-50384; a patch is available from the vendor and the exact patched build numbers for each affected OS are listed in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50384 (the input does not provide a single fix version, so consult the advisory for the KB/build matching your specific Windows release). Prioritize multi-user and shared systems such as Remote Desktop Session Hosts. As a compensating control where patching must be delayed, you can disable clipboard history and cloud clipboard (Settings > System > Clipboard, or via the 'Allow Clipboard History' / 'Allow Clipboard synchronization across devices' Group Policies), which reduces exposure of the Clip Service functionality - the trade-off is loss of clipboard-history and cross-device clipboard features for users. Because this is a local EoP requiring an existing account, also enforce least privilege and restrict who can run code on affected hosts to limit the pool of potential attackers.
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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