EUVD-2026-44005
GHSA-wf5r-2qwx-c42p
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local authenticated user (AV:L/PR:L) must win a hard-to-time race (AC:H) with no user interaction, achieving full SYSTEM-level compromise (C:H/I:H/A:H).
Primary rating from Vendor (microsoft).
CVSS VectorNVD
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
5DescriptionNVD
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows USB Print Driver allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows USB Print Driver affects Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025, where a race condition (CWE-362) in the handling of a shared resource lets an already-authenticated local user win a timing window to execute code at higher privilege. Rated CVSS 7.0 with high attack complexity, it requires low privileges and no user interaction, yielding full confidentiality, integrity, and availability impact. There is no public exploit identified at time of analysis, SSVC exploitation status is 'none', and EPSS is low at 0.19% (9th percentile), consistent with a Microsoft-reported, patch-first disclosure.
Technical ContextAI
The flaw lives in the Windows USB printing subsystem - the kernel-mode/user-mode driver stack that services USB-connected print devices. CWE-362 (Concurrent Execution Using Shared Resource with Improper Synchronization) means two or more threads access a shared object without adequate locking, creating a time-of-check-to-time-of-use window an attacker can race to manipulate state (for example, swapping or corrupting a handle, buffer, or privilege context between validation and use). The CPE data scopes this to Microsoft OS builds only - cpe:2.3:a:microsoft:windows_11_version_24h2, 25h2, 26h1, windows_server_2025, and its Server Core installation - indicating a platform driver defect rather than a third-party component. Because print drivers frequently run with elevated privileges, winning the race can promote a low-privileged process to SYSTEM-level capability.
RemediationAI
Apply the Microsoft security update that raises each affected build to at least the fixed version: Windows 11 24H2 to 10.0.26100.8875, Windows 11 25H2 to 10.0.26200.8875, Windows 11 26H1 to 10.0.28000.2525, and Windows Server 2025 (including Server Core) to 10.0.26100.33158; details and download packages are in the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-54991 (Patch available per vendor advisory, exact fix builds confirmed by EUVD version ranges). Because exploitation requires local authenticated access, interim compensating controls include restricting interactive and local logon rights on servers to trusted administrators, minimizing multi-user/shared-host exposure, and - where USB printing is not needed - disabling or blocking USB print device installation via Group Policy device installation restrictions or by disabling the USB print class driver, with the trade-off that USB-attached printers will stop functioning for that host. These controls reduce the attack surface only; the update is the definitive fix and should be prioritized on shared and privileged systems.
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Same weakness CWE-362 – Race Condition
View allSame technique Race Condition
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External POC / Exploit Code
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