CVE-2025-50167: Windows 10 1507 Privilege Escalation Flaw

CVE-2025-50167 Overview

CVE-2025-50167 is a race condition vulnerability in Windows Hyper-V that allows an authorized local attacker to elevate privileges. The flaw stems from concurrent execution using a shared resource with improper synchronization [CWE-362]. An attacker with low-privileged local access can exploit the timing window to gain higher privileges on the host system.

Microsoft published the advisory on August 12, 2025. The vulnerability affects a wide range of Windows client and server versions that support Hyper-V, including Windows 10, Windows 11, and Windows Server editions from 2012 through 2025.

Critical Impact
Successful exploitation grants an authenticated local attacker high impact on confidentiality, integrity, and availability, enabling full privilege escalation on the Hyper-V host.

Affected Products

Microsoft Windows 10 (versions 1507, 1607, 1809, 21H2, 22H2)
Microsoft Windows 11 (versions 22H2, 23H2, 24H2)
Microsoft Windows Server 2012, 2016, 2019, 2022, 2022 23H2, and 2025

Discovery Timeline

2025-08-12 - CVE-2025-50167 published to NVD and Microsoft releases security update
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-50167

Vulnerability Analysis

The vulnerability resides in Windows Hyper-V, the native Type-1 hypervisor that provides hardware virtualization on Windows client and server platforms. Hyper-V mediates access between guest virtual machines and host physical resources through virtualization service providers running in the root partition.

Because the flaw is classified as [CWE-362] Concurrent Execution using Shared Resource with Improper Synchronization, exploitation requires an attacker to win a narrow timing window between two operations that access the same resource. The high attack complexity reflects the need to reliably trigger the race condition rather than a simple linear exploit path.

Successful exploitation results in local privilege escalation with high impact on confidentiality, integrity, and availability. Because Hyper-V components run at high privilege on the host, a race-condition win can escalate a low-privileged user process to SYSTEM or higher trust contexts.

Root Cause

The root cause is missing or improper synchronization around a shared resource within Hyper-V. When two code paths access the resource concurrently without adequate locking, an attacker-controlled thread can modify state between the time it is checked and the time it is used, corrupting the resource or bypassing an authorization decision.

Attack Vector

The attack vector is local. An attacker must already hold low privileges on the target system, such as a standard user account or code execution inside a guest VM context that maps to host-side Hyper-V structures. No user interaction is required. Exploitation involves repeatedly triggering the vulnerable Hyper-V code path while a second thread races to modify shared state at the critical instant. Microsoft has not published exploit details; refer to the Microsoft Security Response Center advisory for authoritative information.

Detection Methods for CVE-2025-50167

Indicators of Compromise

Unexpected creation of processes running as SYSTEM or NT AUTHORITY spawned from low-privileged user sessions on Hyper-V hosts
Abnormal loading or unloading of Hyper-V related drivers such as vmbus.sys, vid.sys, or hvix64.exe activity outside scheduled maintenance
Repeated, high-frequency calls to Hyper-V IOCTLs or hypercalls from a single non-administrative process, consistent with race-condition brute-forcing

Detection Strategies

Monitor for privilege escalation patterns where a standard user token is replaced by an elevated token in the same process tree without a legitimate elevation prompt
Correlate Windows Event Log entries in Microsoft-Windows-Hyper-V-* channels with process telemetry to identify anomalous VM management activity from unauthorized principals
Deploy behavioral detection tuned to identify tight exploitation loops targeting virtualization interfaces from unsigned or newly observed binaries

Monitoring Recommendations

Enable and forward Hyper-V operational, hypervisor, and worker event logs to a centralized SIEM for longitudinal analysis
Baseline normal Hyper-V API and hypercall usage per host so that anomalous burst patterns from user-mode processes surface quickly
Alert on new local administrator or service account creations on Hyper-V hosts, particularly following suspicious process activity

How to Mitigate CVE-2025-50167

Immediate Actions Required

Apply the August 2025 Microsoft security updates referenced in the MSRC advisory for CVE-2025-50167 to all Hyper-V enabled Windows hosts
Prioritize patching on multi-tenant Hyper-V hosts and systems where untrusted users have local logon rights
Audit local accounts and remove unnecessary interactive logon privileges on Hyper-V hosts to reduce the pool of potential attackers

Patch Information

Microsoft has released cumulative security updates addressing CVE-2025-50167 across all affected Windows client and server editions. Administrators should consult the Microsoft CVE-2025-50167 Update Guide to identify the specific KB article and build number applicable to each deployed Windows version and install through Windows Update, WSUS, or the Microsoft Update Catalog.

Workarounds

Where patching cannot be completed immediately, restrict local logon on Hyper-V hosts to trusted administrators only through Group Policy user rights assignment
On systems that do not require virtualization, disable the Hyper-V role and hypervisor via bcdedit /set hypervisorlaunchtype off and remove the Hyper-V feature to eliminate the vulnerable attack surface
Enforce application allowlisting on Hyper-V hosts to block execution of unauthorized binaries that could carry race-condition exploit code

bash

# Disable Hyper-V hypervisor launch as a temporary mitigation on non-virtualization hosts
bcdedit /set hypervisorlaunchtype off

# Remove the Hyper-V Windows feature (requires reboot)
Disable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All

# Verify installed updates address CVE-2025-50167
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