Microsoft Patches Multiple Windows CLFS Driver Privilege Escalation Flaws

Microsoft disclosed and patched multiple elevation-of-privilege vulnerabilities in the Windows Common Log File System (CLFS) Driver, including CVE-2026-40407, CVE-2025-62470, and CVE-2025-32713. The most detailed advisory, for CVE-2026-40407, describes a heap-based buffer overflow (CWE-122) that allows a locally authenticated low-privilege attacker to escalate to SYSTEM without user interaction.

Microsoft rated CVE-2026-40407 as Important with a CVSS 3.1 score of 7.8, citing high impact to confidentiality, integrity, and availability. The company said the flaw had not been publicly disclosed and was not being exploited in the wild at the time of publication, assessed exploitation as unlikely, and released an official security update to remediate the issue; the related CLFS advisories indicate a continuing pattern of privilege-escalation risk in this Windows component.