CVE-2025-32701

CVE-2025-32701 is a use-after-free (CWE-416) in the Windows Common Log File System (CLFS) driver, a kernel component that manages log files for Windows and third-party applications. An attacker who already has valid low-privileged access to a target machine can trigger the flaw through local operations against the CLFS driver, with no user interaction required. Successful exploitation allows elevation of privileges on the local system, with high impact on confidentiality, integrity, and availability (typically yielding SYSTEM-level rights). Any organization running the affected Windows 10/11 client releases or Windows Server 2008/2012/2016/2019 is in scope, which covers effectively the entire supported Windows installed base. Microsoft patched the flaw in the May 2025 Patch Tuesday release as one of five zero-days under active exploitation, and CISA added it to the Known Exploited Vulnerabilities catalog on May 13, 2025; no public proof-of-concept is known and ransomware use has not been confirmed.

What to do: Apply Microsoft's May 2025 Patch Tuesday security updates (released May 13, 2025) to every affected Windows 10/11 and Windows Server system and verify installation across the fleet, prioritizing multi-user servers, RDS hosts, and shared workstations where any local user or malware could leverage it for SYSTEM-level access. Because exploitation requires a local foothold, treat this bug as a prime chaining target for other exploits and malware; with no public PoC and no documented workaround in the data, patching is the only reliable mitigation, and defenders should hunt for anomalous CLFS driver activity on unpatched hosts.