🚨 Critical Windows Zero-Day (CVE-2025-62221) Actively Exploited: Patch Now

Date: December 13, 2025

Severity: High (CVSS 7.8)

Impact: Local Privilege Escalation (SYSTEM Access)

Microsoft has confirmed that a new zero-day vulnerability, tracked as CVE-2025-62221, is being actively exploited in the wild. This flaw exists in the Windows Cloud Files Mini Filter Driver, a core component used to manage cloud-backed files (like those used by OneDrive, iCloud, and SharePoint).

Why This is Dangerous

The vulnerability is a “Use-After-Free” memory flaw. While it requires an attacker to already have a foothold on the system (local access), it allows them to bypass security boundaries and gain SYSTEM privileges—the highest level of authorization on a Windows machine.

• No User Interaction: The exploit can be triggered without the victim clicking a link or opening a file.
• Low Complexity: Security researchers note the attack is relatively simple to execute once an attacker is on the machine.
• Widespread Impact: The affected driver is present on almost all modern versions of Windows, including Windows 11, Windows 10, and Windows Server 2025.

The December “Zero-Day Trio”

While CVE-2025-62221 is the only one currently seeing active exploitation, Microsoft also patched two other zero-days that were publicly disclosed prior to the fix:

1. CVE-2025-54100 (PowerShell): A remote code execution flaw that can be triggered if a user runs a malicious command.
2. CVE-2025-64671 (GitHub Copilot for JetBrains): A command injection flaw affecting AI-assisted developer environments.

Immediate Recommendations

The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added the primary zero-day to its Known Exploited Vulnerabilities (KEV) catalog, mandating that federal agencies patch by December 30, 2025.

For businesses and home users:

• Run Windows Update immediately: Navigate to Settings > Windows Update > Check for updates.
• Prioritize Servers: Ensure all Windows Servers, especially those acting as file or cloud sync hosts, are updated and rebooted.
• Verify PowerShell 5.1 Updates: Ensure your PowerShell environment is updated to include the new security warnings for the Invoke-WebRequest command.