Microsoft Fixes Exploited Zero Day in Light Patch Tuesday

Microsoft has fixed an exploited zero-day in this month’s lighter Patch Tuesday, with the actively exploited flaw identified as CVE-2025-62221, which Microsoft notes has a CVSS score of 7.8 and affects the Windows Cloud Files Mini Filter Driver, enabling a privilege escalation for an already-authenticated attacker.

Attackers are already exploiting this vulnerability, and PoC exploits are publicly available for two other flaws patched this week: CVE-2025-54100, a PowerShell remote code execution, and CVE-2025-64671, another RCE affecting the GitHub Copilot for JetBrains code completion tools, though these PoCs are deemed relatively low risk for exploitation by Microsoft.

The piece also notes that 2025 patches total more than 1,150, making it one of the year’s biggest patch tallies, with several high-risk flaws being privilege elevation issues. Security professionals urged prioritisation of the PowerShell and Copilot-related bugs, given their potential impact on enterprise networks. This update—dated 9 December 2025—follows December’s broader patch cycle, described as lightweight by analysts, according to Fortra.