Patch Tuesday December 2025

Patch Tuesday December 2025 – 3 Zero-Days (1 Actively Exploited)

Microsoft has issued security updates for 56 flaws, including three Zero-Day vulnerabilities (one actively exploited and two publicly disclosed) as part of the Patch Tuesday updates for December 2025.

Zero-Days Fixed

The most critical patches address three flaws already being used or exposed to the public:

1. Actively Exploited Zero-Day (EoP)

• CVE-2025-62221 - Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability.
• Impact: This use-after-free flaw allows an attacker who has already gained basic access to a system to elevate their privileges to SYSTEM (full control). This must be patched immediately.

1. Publicly Disclosed Zero-Days (RCE & AI Risk)

• CVE-2025-64671 - GitHub Copilot for JetBrains Remote Code Execution Vulnerability.
• Impact: An RCE vulnerability that exposes developer environments to risk, highlighting the emerging security challenges with AI coding assistants.
• CVE-2025-54100 - Windows PowerShell Remote Code Execution Vulnerability
• Impact: A command injection flaw that could allow an attacker to execute arbitrary code remotely if a user is persuaded to run a crafted PowerShell command.

Critical Vulnerabilities to Prioritise

Beyond the zero-days, two Critical Remote Code Execution (RCE) flaws in Microsoft Office demand immediate attention:

• CVE-2025-62557 - Microsoft Office Critical RCE
• CVE-2025-62554 - Microsoft Office Critical RCE

These can often be exploited simply by opening a malicious document or viewing a crafted email in the Outlook Preview Pane.

Vulnerabilities by Category

The December 2025 updates addressed a total of 56 flaws, categorized as follows:

• Elevation of Privilege Vulnerabilities - 28
• Remote Code Execution Vulnerabilities - 19
• Information Disclosure Vulnerabilities - 4
• Denial of Service Vulnerabilities - 3
• Spoofing Vulnerabilities - 2
• Total Flaws - 56

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Originally published on LinkedIn.