EUVD-2026-43880
GHSA-pjvc-v637-5rjg
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local post-auth escalation (AV:L/PR:L) gated by a hard-to-win race (AC:H), no user interaction, yielding full kernel compromise (C:H/I:H/A:H) within the same host (S:U).
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows USB Driver allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Microsoft Windows USB driver stack lets an already-authenticated low-privileged user win a race condition (CWE-362) to gain SYSTEM-level control across Windows 10 (1607-22H2), Windows 11 (24H2/25H2/26H1), and Windows Server 2012 through 2025. 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. EPSS is low (0.19%, 9th percentile) and SSVC rates exploitation as none but technical impact as total, indicating high damage potential if a working exploit is developed.
Technical ContextAI
The flaw is a concurrent-execution race condition (CWE-362) in the Windows USB driver - kernel-mode code that mediates enumeration and I/O for USB devices. Improper synchronization over a shared resource (e.g., a time-of-check-to-time-of-use window on a shared buffer or device object) allows a caller to manipulate state between validation and use, corrupting kernel memory or object references. Because USB handling runs in ring-0, successful exploitation yields code execution in the kernel context. The affected CPEs span the full modern Windows line: cpe:2.3:a:microsoft:windows_10_version_1607 through windows_11_version_26h1, plus Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025 including Server Core installations, confirming this is core-OS driver code rather than an optional component.
RemediationAI
Patch available per vendor advisory - apply the Microsoft cumulative update that raises each build past the fixed threshold listed by MSRC/EUVD (for example Windows 11 24H2 to 10.0.26100.8875 or later, Windows Server 2025 to 10.0.26100.33158 or later, Windows 10 21H2/22H2 to 10.0.19044.7548/10.0.19045.7548, and Windows Server 2012 R2 to 6.3.9600.23291); confirm the exact KB and build for your edition at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50321. Because exploitation requires local low-privileged access and there is no vendor-published standalone workaround, interim compensating controls target that access path: enforce least privilege and strong endpoint access controls to limit who can run local code, and where USB is not operationally required, restrict USB device installation via Group Policy (Prevent installation of removable devices) - with the trade-off that this breaks legitimate USB peripherals and does not fully cover already-present device objects, so it is a stopgap, not a substitute for the update.
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Same weakness CWE-362 – Race Condition
View allSame technique Information Disclosure
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External POC / Exploit Code
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