CVE-2025-24059: Windows 10 1507 Privilege Escalation Flaw

CVE-2025-24059 Overview

CVE-2025-24059 is a local elevation of privilege vulnerability in the Windows Common Log File System (CLFS) driver. The flaw stems from an incorrect conversion between numeric types [CWE-125] within the kernel driver responsible for transaction logging. An authenticated local attacker can exploit this weakness to elevate privileges to SYSTEM, gaining full control over the affected host.

Microsoft published the advisory on March 11, 2025. The vulnerability affects the entire supported Windows client and server product line, from Windows 10 1507 through Windows 11 24H2 and Windows Server 2008 through Windows Server 2025.

Critical Impact

Successful exploitation grants SYSTEM-level privileges on the local machine, enabling attackers to disable security controls, install persistent implants, and pivot deeper into the environment.

Affected Products

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

Discovery Timeline

• 2025-03-11 - CVE-2025-24059 published to NVD and Microsoft releases security patch
• 2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-24059

Vulnerability Analysis

The Common Log File System is a Windows kernel subsystem that provides high-performance, general-purpose transaction logging. Applications and kernel components use CLFS through the clfs.sys driver to write structured log records. Because CLFS handlers execute in kernel mode, any memory-safety defect in the driver directly translates into a privilege escalation primitive.

CVE-2025-24059 originates from an improper numeric type conversion during log record processing. When a smaller or signed integer is converted to a wider or unsigned type without proper bounds validation, the resulting value can misrepresent buffer sizes or offsets. This mismatch leads to out-of-bounds memory access, categorized under [CWE-125].

Root Cause

The defect lies in the kernel-mode handling of CLFS log metadata, where a numeric conversion produces a value that no longer reflects the true size of an associated buffer. Subsequent operations that trust this value perform reads beyond the intended memory region. Attackers can shape the surrounding kernel memory to convert the out-of-bounds condition into arbitrary write or code execution primitives.

Attack Vector

Exploitation requires local access and low-privileged authenticated execution on the target system. An attacker running a malicious binary can craft a specially formed CLFS log file and issue driver requests that trigger the flawed conversion path. The vulnerability does not require user interaction. CLFS bugs have historically been favored by ransomware operators and access brokers because they provide a reliable path from a foothold to SYSTEM. This class of driver flaw is commonly chained with initial access techniques such as phishing, malicious document execution, or exploitation of a public-facing service.

No public proof-of-concept exploit has been published at the time of writing, and the vulnerability is not currently listed in the CISA Known Exploited Vulnerabilities catalog. The EPSS probability is 0.509%.

Detection Methods for CVE-2025-24059

Indicators of Compromise

• Unexpected creation or modification of CLFS log files (.blf, .clfs) in user-writable directories such as %TEMP% or %APPDATA%.
• Unsigned or newly deployed binaries invoking CreateLogFile, AddLogContainer, or related CLFS APIs shortly before a privilege elevation event.
• Process token elevation to NT AUTHORITY\SYSTEM originating from a non-service, low-integrity parent process.
• Kernel stack traces or bugcheck dumps referencing clfs.sys following anomalous user-mode activity.

Detection Strategies

• Hunt for low-privileged processes that spawn SYSTEM-level child processes without a legitimate service-hosting parent (services.exe, svchost.exe).
• Correlate CLFS API usage from non-standard binaries with subsequent security-tool tampering or persistence installation.
• Baseline the set of processes that legitimately open handles to \Device\Clfs and alert on deviations.

Monitoring Recommendations

• Enable and forward Windows kernel-mode driver telemetry, process creation events (Event ID 4688 with command line), and Sysmon Event IDs 1 and 11 to a centralized analytics platform.
• Monitor for repeated clfs.sys crashes in Windows Reliability logs, which can indicate exploitation attempts or fuzzing.
• Track new admin or SYSTEM logons that follow closely after standard-user process activity on the same host.

How to Mitigate CVE-2025-24059

Immediate Actions Required

• Apply the March 2025 Microsoft security update for every affected Windows client and server SKU without delay.
• Prioritize patching on multi-user systems, jump hosts, RDP servers, and developer workstations where local access is broadly available.
• Audit local user and service account permissions and remove unnecessary interactive logon rights.
• Enforce application allowlisting to prevent execution of unsigned attacker binaries that would trigger the CLFS code path.

Patch Information

Microsoft addressed CVE-2025-24059 in the March 11, 2025 Patch Tuesday release. Refer to the Microsoft Security Update Guide for CVE-2025-24059 for the specific KB articles that apply to each supported Windows version.

Workarounds

• No official workaround exists; patching is the only supported remediation.
• Reduce exposure by restricting local logon rights and enforcing least-privilege on endpoints and servers.
• Deploy behavioral endpoint protection capable of identifying kernel exploitation patterns and blocking privilege-escalation chains.

# Verify the CLFS driver version on a Windows host to confirm patch deployment
powershell -Command "Get-Item C:\Windows\System32\drivers\CLFS.sys | Select-Object VersionInfo"

# List installed security updates and confirm the March 2025 rollup is present
wmic qfe list brief /format:table