Article
December 2025 Patch Tuesday: Key Vulnerabilities Overview
Introduction
Every second Tuesday of the month, Microsoft rolls out its latest security updates in what’s called ‘Patch Tuesday.’ It’s like a monthly wellness check-up for your tech. This December, Microsoft addressed several key security threats that could impact your devices and data. In this article, we’ll break down what these new patches mean, highlight the most critical vulnerabilities, and wrap up with simple steps you can take to protect yourself.
Summary of December 2025 Patch Tuesday
This month’s Patch Tuesday is critical, featuring a total of 57 vulnerabilities. Among these, three are zero-day vulnerabilities, which means they were being exploited before Microsoft released a fix. Notably, issues in the Cloud Files Mini Filter and Microsoft Office received significant attention due to their potential risks. The general advice is clear: patch now to protect against threats, especially if you use services or devices that connect to the internet.
Understanding these updates is crucial in protecting enterprise environments. Below, we categorize the vulnerabilities based on their exposure to the internet.
Updates are listed according to their CVSS Score
Exposed to internet 
December 2025 Patch Tuesday
Internal Network
Exposed to the Internet
GitHub Copilot for Jetbrains – Remote Code Execution
A remote code execution vulnerability allows command injection via GitHub Copilot when used with Jetbrains IDEs. GitHub Copilot is an AI-based tool that aids developers by suggesting code fragments based on the current context.
Windows Routing and Remote Access Service (RRAS) – Remote Code Execution
A remote code execution vulnerability exists in Windows RRAS, exploitable through user interaction with a specially crafted server response. RRAS supports VPN servers and routing capabilities, crucial for network administration in Windows environments.
Windows Resilient File System (ReFS) – Remote Code Execution
A remote code execution vulnerability in ReFS involves a heap-based buffer overflow. ReFS is designed for data availability, efficient scaling across large datasets, and maintaining data integrity.
Windows Cloud Files Mini Filter Driver – Privilege Escalation
A privilege escalation vulnerability in the Windows Cloud Files Mini Filter Driver allows attackers to elevate to SYSTEM privileges due to improper handling. This driver is a core component of Windows, enabling cloud applications like OneDrive and iCloud to access file system functionalities.
Internal Network
Microsoft Office – Remote Code Execution
A critical remote code execution vulnerability in Microsoft Office can be exploited by viewing a crafted email in the Preview Pane, potentially leading to unauthorized code execution. Microsoft Office is a suite of productivity applications, including Word, Excel, PowerPoint, and Outlook.
Microsoft Office – Remote Code Execution
This critical remote code execution vulnerability in Microsoft Office is triggered by opening a crafted document. Microsoft Office is widely used for business productivity, offering tools for document creation and management.
Windows Win32k – Elevation of Privilege
An elevation of privilege vulnerability exists in the Windows Win32k subsystem, potentially exploited to gain unauthorized privilege levels. Win32k manages the display of graphics and text on display devices within Windows.
Windows Common Log File System Driver – Elevation of Privilege
This elevation of privilege vulnerability is found in the Windows Common Log File System Driver, a component that allows applications to log, record, view, and write log records efficiently, compromising system security.
Windows PowerShell – Remote Code Execution
A remote code execution vulnerability exists in Windows PowerShell, allowing unauthorized users to execute code via command injection. PowerShell is a task automation framework comprising a command-line shell and scripting language used to automate and configure system tasks.
Microsoft Office Outlook – Remote Code Execution
A remote code execution vulnerability is present in Microsoft Outlook, involving a use-after-free error which requires email interaction. Outlook is a widely used email client and personal information manager, integral to business communications.
Conclusion
To safeguard your systems, ensure you install these patches promptly. These updates are crucial for maintaining security and privacy. Always back up your data and stay alert to potential phishing attempts. Keeping your software updated minimizes risks and helps secure your digital life.
Have questions about implementing these patches or securing your IT environment? Schedule a call with At-Bay’s Advisory Services team to get started.
About CVSS
The Common Vulnerability Scoring System (CVSS) is an industry-standard framework for evaluating and communicating the severity of software vulnerabilities. It provides a numerical score that helps organizations prioritize and address security issues effectively. CVSS scores quantify the severity of a vulnerability on a scale from 0 (no severity) to 10 (critical severity). CVSS considers multiple factors, including; Exploitability, Impact, Exploit code maturity, Remediation level, Report confidence. The system enables organizations to compare and prioritize vulnerabilities based on their potential impact on IT infrastructure.
References
- https://msrc.microsoft.com/update-guide/releasenote/2025-dec
- https://www.rapid7.com/blog/post/em-patch-tuesday-december-2025/
- https://blog.talosintelligence.com/microsoft-patch-tuesday-december-2025/
- https://krebsonsecurity.com/2025/12/microsoft-patch-tuesday-december-2025-edition/
- https://www.bleepingcomputer.com/news/microsoft/microsoft-december-2025-patch-tuesday-fixes-3-zero-days-57-flaws