EUVD-2025-17791
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3Tags
Description
Heap-based buffer overflow in Windows Common Log File System Driver allows an authorized attacker to elevate privileges locally.
Analysis
Heap-based buffer overflow vulnerability in the Windows Common Log File System (CLFS) Driver that allows local authenticated attackers to achieve privilege escalation with high confidence of exploitation. The vulnerability affects Windows systems with the CLFS driver enabled and requires local access with standard user privileges; successful exploitation grants complete system compromise including code execution at SYSTEM level. While no public POC is confirmed in available intelligence, the straightforward nature of heap overflows and the high CVSS score (7.8) with low attack complexity indicate active research interest and potential for rapid weaponization.
Technical Context
The Common Log File System (CLFS) is a Windows kernel-mode driver component that provides a high-performance, general-purpose logging mechanism used by various Windows subsystems. CLFS is implemented in clfs.sys and processes kernel-level logging requests through system calls. The vulnerability is classified as CWE-122 (Heap-based Buffer Overflow), indicating that improper bounds checking in memory allocation or data copying operations within the CLFS driver allows an attacker-controlled buffer to overflow heap memory. This specific class of vulnerability in kernel drivers is particularly dangerous because: (1) heap metadata corruption can lead to arbitrary code execution, (2) kernel execution context means privilege level escalation to SYSTEM, and (3) the driver operates at ring-0 privilege level. The root cause likely stems from insufficient validation of log record sizes, transaction parameters, or user-supplied data passed through CLFS IOCTLs without proper length verification before heap operations.
Affected Products
Based on CLFS driver scope: (1) Windows 10 (all versions, including 21H2), (2) Windows 11 (all versions), (3) Windows Server 2016, 2019, 2022. CPE strings would include: cpe:2.3:o:microsoft:windows_10:*:*:*:*:*:*:*:*, cpe:2.3:o:microsoft:windows_11:*:*:*:*:*:*:*:*, cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*, cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*, cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*. Specific version information and patch dates should be cross-referenced with Microsoft Security Advisory references. The vulnerability affects default installations where CLFS is enabled (standard configuration); only systems with CLFS driver explicitly disabled are unaffected.
Remediation
Immediate actions: (1) Apply Windows security updates released by Microsoft addressing CVE-2025-32713—patches will update clfs.sys with bounds checking fixes; (2) If patch unavailable, implement access controls restricting local login to trusted users only, disabling unnecessary local accounts and guest access; (3) Monitor for exploitation attempts via Event ID 4688 (process creation) and kernel debugging logs for clfs.sys exceptions. Specific patch versions should be obtained from Microsoft Security Updates portal—Windows Update or WSUS deployment recommended. For systems unable to patch immediately: disable CLFS if not required (requires reboot and verification of dependent services), implement device guard/credential guard to isolate processes, and apply AppLocker policies restricting execution of suspicious applications. Long-term: maintain current Windows patching cadence and subscribe to Microsoft Security Response Center advisories.
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External POC / Exploit Code
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