CVE-2025-59220: Windows 10 Privilege Escalation Flaw

CVE-2025-59220 Overview

CVE-2025-59220 is a race condition vulnerability in the Windows Bluetooth Service that allows an authorized local attacker to elevate privileges. The flaw stems from concurrent execution using a shared resource with improper synchronization [CWE-362]. A successful exploit yields high impact to confidentiality, integrity, and availability on the affected host. Microsoft published the advisory on September 18, 2025, covering Windows 10, Windows 11, and Windows Server 2022 and 2025 editions. Exploitation requires local access and low privileges, but attack complexity is high because the attacker must reliably win the race window. No public proof-of-concept or in-the-wild exploitation has been reported.

Critical Impact
Successful exploitation lets a low-privileged local user gain SYSTEM-level privileges on the affected Windows host through the Bluetooth Service.

Affected Products

Microsoft Windows 10 21H2 and 22H2
Microsoft Windows 11 22H2, 23H2, and 24H2
Microsoft Windows Server 2022, Server 2022 23H2, and Server 2025

Discovery Timeline

2025-09-18 - CVE-2025-59220 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-59220

Vulnerability Analysis

The Windows Bluetooth Service handles device pairing, connection state, and I/O for Bluetooth peripherals under a privileged service context. CVE-2025-59220 exists because multiple threads or code paths within the service access a shared resource without adequate synchronization primitives. An authorized local attacker who repeatedly triggers the vulnerable code path can interleave operations so that state validation and state use fall out of order. The resulting time-of-check to time-of-use (TOCTOU) condition permits the attacker to influence a privileged operation, corrupting service state or executing code in the security context of the Bluetooth Service. The attack is local only; network exploitation is not possible.

Root Cause

The root cause is improper synchronization of a shared resource within the Windows Bluetooth Service [CWE-362]. Concurrent code paths lack the locking or atomic guarantees required to serialize access. When two operations race, the service processes attacker-controlled data in a privileged code path that assumed the data had already been validated or was owned by a trusted caller.

Attack Vector

Exploitation requires an interactive or programmatic local session with low privileges. The attacker issues concurrent requests to the Bluetooth Service and repeatedly triggers the race window until timing favors the malicious ordering. High attack complexity reflects the timing sensitivity and the need to reproduce the race consistently. No user interaction is required. The specific exploitation mechanism and race window are not detailed in Microsoft's public advisory. Refer to the Microsoft CVE-2025-59220 Advisory for vendor guidance.

Detection Methods for CVE-2025-59220

Indicators of Compromise

Unexpected crashes, hangs, or restarts of the bthserv (Bluetooth Support Service) process on endpoints where Bluetooth is not in active use.
New processes or threads spawned by svchost.exe hosting the Bluetooth Service that subsequently perform privileged actions unrelated to Bluetooth I/O.
Local user accounts gaining SYSTEM-level access shortly after issuing repeated Bluetooth API calls or device enumeration requests.

Detection Strategies

Baseline normal Bluetooth Service activity per host and alert on sustained bursts of concurrent Bluetooth API calls from a single user session.
Correlate Windows Service Control Manager events (Event IDs 7031, 7034) for bthserv with subsequent privilege changes in Security event logs.
Hunt for child processes of the Bluetooth Service svchost.exe instance that do not match the expected binary set.

Monitoring Recommendations

Ingest Windows System, Security, and Application logs into a centralized platform and retain them for correlation across the local privilege escalation kill chain.
Monitor process creation events (Event ID 4688 or Sysmon Event ID 1) for anomalous descendants of the Bluetooth Service host process.
Track unpatched Windows build numbers across the fleet to prioritize hosts still exposed to CVE-2025-59220.

How to Mitigate CVE-2025-59220

Immediate Actions Required

Apply the Microsoft September 2025 security update that addresses CVE-2025-59220 to all affected Windows client and server builds.
Prioritize patching multi-user systems, jump hosts, and shared workstations where local users are most likely to attempt privilege escalation.
Audit local account membership and remove unnecessary interactive logon rights on servers and privileged endpoints.

Patch Information

Microsoft has released security updates for all affected Windows versions. Consult the Microsoft CVE-2025-59220 Advisory for the specific KB article and build numbers that correspond to each supported release of Windows 10, Windows 11, Windows Server 2022, and Windows Server 2025.

Workarounds

On systems that do not require Bluetooth functionality, disable the Bluetooth Support Service (bthserv) and set its startup type to Disabled to eliminate the attack surface.
Restrict local logon rights through Group Policy so that only trusted administrative accounts can execute code on servers hosting the vulnerable service.
Where feasible, remove or disable Bluetooth radios in firmware or BIOS on servers that have no operational need for wireless peripherals.

bash

# Disable the Bluetooth Support Service on hosts that do not require Bluetooth
sc.exe config bthserv start= disabled
sc.exe stop bthserv