CVE-2025-49730: Windows 10 1507 Privilege Escalation Flaw

CVE-2025-49730 Overview

CVE-2025-49730 is a Time-of-Check Time-of-Use (TOCTOU) race condition in the Microsoft Windows Quality of Service (QoS) scheduler. An authorized local attacker can exploit this race window to elevate privileges on the affected system. The flaw is tracked under CWE-122 (Heap-based Buffer Overflow) in the National Vulnerability Database, indicating that the race condition triggers a memory corruption condition in kernel-adjacent scheduling code. Microsoft has confirmed the issue across a broad range of Windows client and server releases through its security advisory.

Critical Impact
A successful exploit grants SYSTEM-level privileges on affected Windows hosts, providing full read, write, and execution access to the operating system.

Affected Products

Microsoft Windows 10 (1507, 1607, 1809, 21H2, 22H2) and Windows 11 (22H2, 23H2, 24H2)
Microsoft Windows Server 2008, 2008 R2, 2012, 2012 R2, 2016, 2019
Microsoft Windows Server 2022, 2022 23H2, and 2025

Discovery Timeline

2025-07-08 - CVE-2025-49730 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-49730

Vulnerability Analysis

The vulnerability resides in the Windows QoS scheduler, a kernel component responsible for prioritizing network traffic and managing scheduling policies. A TOCTOU race condition exists between the validation of a scheduling object or buffer and its subsequent use. An attacker who wins the race can substitute the validated data with attacker-controlled content before the scheduler consumes it. This mismatch leads to a heap-based memory corruption condition tracked as CWE-122. Successful exploitation results in elevation of privilege from a low-privileged local user context to SYSTEM.

Root Cause

The root cause is a non-atomic sequence in the QoS scheduler where a resource is checked and then used without proper locking or reference protection. During the interval between the check and the use, a concurrent thread can modify the underlying object, size field, or pointer. When the scheduler operates on the mutated state, it writes past an allocated heap buffer or dereferences an unexpected structure.

Attack Vector

Exploitation requires local access with valid low-privileged credentials. The attacker runs a program that repeatedly invokes the vulnerable QoS scheduler code path while a second thread races to replace the validated input. Reliable exploitation is generally achieved with a heap-grooming primitive that shapes adjacent allocations so that the corrupted write overlaps a target kernel object. No user interaction is required beyond executing the exploit binary. An exploit entry has been referenced in public databases, though CISA has not added the issue to the Known Exploited Vulnerabilities catalog.

No verified public proof-of-concept code is available at this time. Refer to the Microsoft CVE-2025-49730 Advisory for the vendor-supplied technical details.

Detection Methods for CVE-2025-49730

Indicators of Compromise

Unexpected creation of SYSTEM-level processes spawned by a standard user session shortly after execution of an unsigned binary.
Kernel bugchecks or unexplained system crashes referencing the QoS scheduler driver or pschedpc components, which can indicate failed exploitation attempts.
Presence of unfamiliar executables in user-writable directories that make repeated calls to QoS or traffic-shaping APIs.

Detection Strategies

Monitor for user-mode processes invoking QoS scheduler interfaces at abnormally high frequency, a behavior consistent with racing the check-to-use window.
Correlate token elevation events (Windows Event ID 4672 for a non-admin user) with recent process creation events (Event ID 4688) from non-standard paths.
Hunt for process trees where a low-privileged parent spawns a child running as NT AUTHORITY\SYSTEM without an intermediate service host.

Monitoring Recommendations

Enable kernel-mode auditing and forward Sysmon Event IDs 1, 10, and 11 to a centralized analytics platform for behavior correlation.
Baseline normal QoS API usage across the environment so that racing-style bursts stand out during triage.
Track patch compliance for all Windows client and server SKUs listed in the Microsoft advisory to reduce dwell risk.

How to Mitigate CVE-2025-49730

Immediate Actions Required

Apply the Microsoft security update referenced in the MSRC advisory for CVE-2025-49730 across all affected Windows client and server systems.
Prioritize patch deployment on multi-user hosts, jump servers, and virtual desktop infrastructure where local user access is expected.
Restrict interactive logon rights to trusted administrative personnel on high-value servers until patching completes.

Patch Information

Microsoft has released security updates for all impacted versions, including Windows 10 (1507 through 22H2), Windows 11 (22H2, 23H2, 24H2), and Windows Server 2008 through Windows Server 2025. Administrators should consult the Microsoft CVE-2025-49730 Advisory for KB numbers matching their specific build and install updates through Windows Update, WSUS, or the Microsoft Update Catalog.

Workarounds

No official workaround has been published by Microsoft; applying the security update is the supported remediation path.
Reduce exposure by enforcing least-privilege policies and removing local administrator rights from standard users on unpatched systems.
Apply application allowlisting to block execution of unsigned binaries from user-writable directories until updates are deployed.

bash

# Verify patch installation status on Windows hosts
Get-HotFix | Where-Object { $_.HotFixID -like 'KB*' } | Sort-Object InstalledOn -Descending

# Enumerate installed updates via WMIC (legacy hosts)
wmic qfe list brief /format:table