EUVD-2026-43823
GHSA-92wq-88hv-346f
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local low-priv attacker (AV:L/PR:L) must win a timing race (AC:H) with no user interaction; successful escalation yields full SYSTEM impact (C:H/I:H/A:H), scope unchanged.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
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 on Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025 allows an already-authenticated local user to win a timing race and elevate to SYSTEM-level privileges. The flaw is a race condition (CWE-362) reported by Microsoft; a vendor patch is available, and there is no public exploit identified at time of analysis. Exploitation is constrained by high attack complexity (winning the race window) but yields full confidentiality, integrity, and availability impact once achieved.
Technical ContextAI
The vulnerability lives in the Windows USB Print Driver, a kernel-mode/user-mode component that services USB-attached printing devices and mediates print I/O between user processes and hardware. The root cause is CWE-362, concurrent execution using a shared resource with improper synchronization ('race condition'): two or more threads access shared driver state without adequate locking, creating a time-of-check-to-time-of-use style window an attacker can manipulate. Because print drivers execute privileged operations on behalf of lower-privileged callers, corrupting or hijacking that shared state during the race can let a low-privileged process influence a privileged code path. The affected CPE set is Microsoft-specific: cpe:2.3:a:microsoft:windows_11_version_24h2, windows_11_version_25h2, windows_11_version_26h1, windows_server_2025, and windows_server_2025_(server_core_installation) - indicating the driver ships in current Windows 11 client branches and the Server 2025 line including Server Core.
RemediationAI
Apply the Microsoft security update for CVE-2026-49802; the input confirms a patch is available from the vendor, and details (including the specific fixed KB per Windows build) are published at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49802 - treat this as the primary and definitive fix (Patch available per vendor advisory; no independent exact fixed-version string was provided in the input, so confirm the KB from MSRC). Where immediate patching is not possible, reduce exposure by limiting who holds interactive local accounts on affected hosts and by restricting local logon on multi-user systems such as Windows Server 2025 and RDS/terminal servers, since exploitation requires local low-privileged access. As a targeted compensating control you can restrict or disable USB device access and USB printing on hosts that do not need it (e.g., via Group Policy device installation restrictions blocking USB print-class devices), which removes the attack surface but breaks legitimate USB printing and any USB peripheral workflows relying on the print stack. Prioritize patching over these workarounds, as they only narrow rather than eliminate the race condition.
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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