CVE-2025-53142 Overview
CVE-2025-53142 is a use-after-free vulnerability [CWE-416] in the Microsoft Brokering File System. The flaw allows an authorized local attacker to elevate privileges on affected Windows systems. Microsoft published the advisory on August 12, 2025.
An attacker with local access and low privileges can trigger the freed-memory reuse condition to gain higher privileges. The attack complexity is high, requiring specific timing or state conditions to succeed. Successful exploitation impacts confidentiality, integrity, and availability of the target host.
Critical Impact
Local privilege escalation to SYSTEM-level access on Windows 11 and Windows Server platforms through memory corruption in the Brokering File System component.
Affected Products
- Microsoft Windows 11 (22H2, 23H2, 24H2)
- Microsoft Windows Server 2022 23H2
- Microsoft Windows Server 2025
Discovery Timeline
- 2025-08-12 - CVE-2025-53142 published to NVD
- 2025-08-12 - Microsoft releases security update for CVE-2025-53142
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-53142
Vulnerability Analysis
The vulnerability resides in the Microsoft Brokering File System, a Windows subsystem that mediates file system operations between processes with different privilege boundaries. A use-after-free condition [CWE-416] occurs when the component references a memory object after that object has been released.
An authorized local user can manipulate object lifecycle handling to reference freed memory during a broker operation. Controlling the contents of the reallocated memory allows the attacker to influence kernel-mode execution flow. This yields code execution in a higher privilege context than the calling process.
The attack requires specific race or state conditions, reflected in the high attack complexity of the CVSS vector. Exploitation is limited to local access, meaning the attacker must already run code on the target host. No user interaction is required for the exploit chain to complete.
Root Cause
The root cause is improper object lifetime management within the Brokering File System driver. The component releases a memory object while a subsequent code path still holds a reference to it. Reuse of the freed allocation creates the exploitable primitive.
Attack Vector
Exploitation requires local, authenticated access to a vulnerable Windows host. An attacker with an initial foothold, obtained through phishing, credential theft, or an existing low-privilege account, can trigger the vulnerable code path. Successful exploitation elevates the process to SYSTEM, enabling credential access, persistence, and lateral movement.
No public proof-of-concept is available at the time of writing. No exploitation in the wild has been confirmed by CISA. Refer to the Microsoft Security Update Guide for vendor technical details.
Detection Methods for CVE-2025-53142
Indicators of Compromise
- Unexpected crashes or bug checks referencing the Brokering File System driver in kernel dump files
- Processes launched with SYSTEM integrity from parent processes running at Medium or Low integrity
- Anomalous handle activity or repeated open/close cycles against broker file system objects from a non-privileged process
Detection Strategies
- Hunt for privilege transitions where a child process token integrity level exceeds the parent process integrity level
- Correlate Windows Error Reporting events tied to bfs.sys or related broker file system components with subsequent privileged process creation
- Baseline normal broker file system API usage per host and alert on statistical outliers by non-privileged users
Monitoring Recommendations
- Enable kernel-mode crash telemetry and forward MiniDump artifacts to a central analysis pipeline
- Ingest Sysmon Event ID 1 (Process Creation) and Event ID 10 (Process Access) into a SIEM for privilege-escalation analytics
- Monitor security event logs for suspicious token manipulation events on Windows 11 and Windows Server 2022/2025 endpoints
How to Mitigate CVE-2025-53142
Immediate Actions Required
- Apply the August 2025 Microsoft security update referenced in the MSRC advisory for CVE-2025-53142 to all affected Windows 11 and Windows Server systems
- Inventory Windows 11 22H2, 23H2, 24H2, Server 2022 23H2, and Server 2025 hosts to identify unpatched systems
- Restrict local logon rights on high-value systems until patching is complete
Patch Information
Microsoft published the security update on August 12, 2025. Consult the Microsoft Security Update Guide entry for CVE-2025-53142 for the specific KB article numbers matching each affected Windows build. Deploy through Windows Update, WSUS, Microsoft Update Catalog, or your endpoint management platform.
Workarounds
- No official workaround has been published by Microsoft; patching is the required remediation path
- Enforce least-privilege policies to limit which users can execute arbitrary code on affected hosts
- Apply application allowlisting through Windows Defender Application Control or AppLocker to reduce the attack surface for local code execution
# Verify installed updates on Windows hosts (PowerShell)
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 10
# Query for missing updates using PSWindowsUpdate module
Get-WindowsUpdate -MicrosoftUpdate
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
