CVE-2025-21391, the zero-day Windows storage flaw, stems from the way Windows resolves file paths and follows links, Walters said. File deletion is just the beginning of the problems it could cause, as it could lead to privilege escalation, unwanted access to security logs or configurations, malware injection, data manipulation, or other attacks.

CISOs should make sure that two actively exploited vulnerabilities in Windows are addressed as part of their staff’s February Patch Tuesday efforts.

Today is Microsoft' 2025 Patch Tuesday, which includes security updates for 55 flaws, including four zero-day vulnerabilities, with two actively exploited in attacks.

Microsoft has rolled out the February 2025 Patch Tuesday updates, KB5051987 and KB5051989, for Windows 11 24H2 and 23H2, as reported by Bleeping Computer. After installing the updates, the build number for Windows 11 version 24H2 will change to Build 26100.