Microsoft Patch Tuesday December 2025: 56 Security Fixes

Every first Tuesday of the month, the tech giant that powers the majority of corporate and personal computing worldwide releases a bundle of security updates that can be collectively called Microsoft Patch Tuesday. This December 2025 edition is no exception, delivering 56 critical fixes that address a broad spectrum of vulnerabilities ranging from privilege escalation to remote code execution. The focus keyword “microsoft patch tuesday” appears early in this discussion to underscore the significance of staying current with these releases.

Overview of the December 2025 Release

Microsoft’s December 2025 patch set represents the largest monthly rollout in the year, covering Windows 10, Windows 11, Windows Server 2019 and 2022, Microsoft Office, Outlook, and even third‑party components such as the GitHub Copilot Plugin for JetBrains. The update package includes 56 individual security fixes, of which 12 are flagged as critical by Microsoft’s own severity grading system. Despite a relatively modest number of public disclosures this month, the cumulative impact of these patches is far from negligible, as several zero‑day vulnerabilities have already been exploited in the wild.

Zero‑Day Vulnerability: CVE‑2025‑62221

The most pressing issue addressed in this batch is CVE‑2025‑62221, a privilege escalation flaw in the Windows Cloud Files Mini Filter Driver. This component is responsible for allowing cloud storage providers such as OneDrive, Google Drive, and iCloud to seamlessly interact with the Windows file system. Because the driver is deeply integrated into core Windows operations, a successful exploitation could grant an attacker elevated rights on a target machine, potentially bypassing standard authentication controls.

Security researchers have highlighted that the vulnerability can be triggered by a crafted file path that is parsed incorrectly by the driver, allowing a local user to elevate privileges. The patch mitigates the issue by tightening the validation logic within the driver’s path handling routine, ensuring that all user‑supplied inputs are properly sanitized before they are processed.

Critical Office and Outlook Vulnerabilities

Three of the most critical flaws involve Microsoft Office and Outlook. The CVE‑2025‑62554 and CVE‑2025‑62557 affect the Office Preview Pane. By simply opening a maliciously crafted email attachment or previewing a compromised document, a user can trigger arbitrary code execution with the privileges of the current user. Although these are classified as “critical,” the attack surface is limited to environments where the Preview Pane is enabled and actively used.

The third critical bug, CVE‑2025‑62562, targets Microsoft Outlook’s message rendering engine. While the preview pane is not the vector for this particular flaw, the vulnerability can still be triggered through a specially crafted email that forces Outlook to execute code during its parsing stage. Microsoft recommends disabling the Preview Pane or applying the latest update to mitigate this risk.

Privilege Escalation Bugs Across Windows Components

Beyond the Office suite, the December patch set includes several privilege escalation vulnerabilities that, while not classified as critical, are likely to be exploited due to their ubiquity and the relative ease of exploitation. These include:

• CVE‑2025‑62458 – Win32k component
• CVE‑2025‑62470 – Windows Common Log File System Driver
• CVE‑2025‑62472 – Windows Remote Access Connection Manager
• CVE‑2025‑59516 – Windows Storage VSP Driver
• CVE‑2025‑59517 – Windows Storage VSP Driver

These components are deeply woven into the fabric of Windows, and attackers often target them to elevate local privileges or gain persistence on compromised machines. The patches introduce stricter input validation and access controls, closing the loopholes that allowed the elevation to occur.

Remote Code Execution in GitHub Copilot Plugin

A standout vulnerability in this release is CVE‑2025‑64671, a remote code execution flaw in the GitHub Copilot Plugin for JetBrains. The plugin, which leverages large language models to assist developers, inadvertently exposed a pathway for malicious code to be executed when the LLM processed a crafted prompt. Attackers could manipulate the plugin’s “auto‑approve” settings to run arbitrary commands on the host system, effectively bypassing user consent.

Security researcher Ari Marzuk coined the term IDEsaster to describe a wave of vulnerabilities affecting integrated development environments. CVE‑2025‑64671 is part of this larger trend, highlighting the need for tighter sandboxing and stricter input validation in AI‑powered coding tools.

Windows PowerShell Remote Code Execution

Another high‑impact flaw is CVE‑2025‑54100, a remote code execution bug in Windows PowerShell that targets Windows Server 2008 and newer. The vulnerability allows an unauthenticated attacker to execute code under the context of the user who launched the PowerShell session. This can be leveraged to perform a wide range of malicious activities, from installing back‑doors to modifying system configurations. The patch adds additional checks to the PowerShell execution engine, preventing unauthorized script execution from untrusted sources.

Applying the Updates: A Practical Guide

While Microsoft’s patching mechanism is designed to be straightforward, organizations with complex environments often face challenges in ensuring that all systems are updated promptly. Below is a step‑by‑step approach to streamline the deployment process:

1. Inventory and Prioritize: Use tools such as Windows Server Update Services (WSUS) or System Center Configuration Manager (SCCM) to generate an inventory of all Windows and Office installations. Prioritize servers and critical infrastructure for immediate patching.
2. Test in a Staging Environment: Before rolling out updates to production, test the patches on a representative subset of machines to catch any compatibility issues with legacy applications.
3. Automate Deployment: Leverage Group Policy or PowerShell scripts to push updates to all endpoints. For PowerShell, the following command can be used to trigger the download and installation of the latest updates:

   Get-WindowsUpdate -MicrosoftUpdate -AcceptAll -Install -AutoReboot

4. Verify Patch Status: After installation, run the Microsoft Update Catalog or use the Windows Update API to confirm that each component is at the latest patch level. A quick check can be performed with:

   wmic qfe list brief /format:table | findstr /i "CVE-2025-"

5. Document and Communicate: Maintain a change log that records which patches were applied, when, and by whom. Communicate any known issues or required workarounds to end‑users.

For a detailed walkthrough of the patching process, refer to Microsoft’s official guide on Windows Update deployment.

Impact on Enterprise Security Posture

Security analysts agree that the cumulative effect of the December 2025 patch set is significant. The inclusion of a zero‑day bug (CVE‑2025‑62221) that was actively exploited in the wild underscores the urgency of applying these updates. Privilege escalation flaws, such as CVE‑2025‑62458 and CVE‑2025‑62470, are particularly insidious because they can be leveraged to move laterally within a network after initial compromise.

Moreover, the GitHub Copilot vulnerability signals a shift in the threat landscape toward AI‑assisted code injection. Developers and DevOps teams must now consider the security implications of third‑party AI tools, especially when they run with elevated privileges or interact with source control systems.

Recommendations for Security Teams

• Implement a zero‑trust model that treats all code, whether human or AI‑generated, as potentially malicious.
• Adopt continuous monitoring solutions that detect anomalous privilege escalation attempts, such as sudden elevation of user rights or unexpected process creation.
• Integrate patch management with vulnerability scanners to automatically flag unpatched systems and prioritize remediation based on CVE severity and exploit availability.

Future Outlook: Preparing for the Next Patch Tuesday

Microsoft’s December 2025 release has set a high bar for the upcoming patch cycles. With over 1,129 vulnerabilities patched in 2025 alone, the company’s commitment to rapid response is evident. However, the sheer volume of updates also highlights the need for robust patch management frameworks that can handle frequent releases without compromising operational stability.

Organizations should also invest in threat hunting capabilities that focus on the types of vulnerabilities addressed in this patch set. For instance, monitoring for unusual file system activity can help detect exploitation attempts related to CVE‑2025‑62221, while scrutinizing PowerShell logs can reveal attempts to leverage CVE‑2025‑54100.

References

• Microsoft Security Response Center – CVE‑2025‑62221
• Microsoft Security Response Center – CVE‑2025‑62554
• Microsoft Security Response Center – CVE‑2025‑62557
• Microsoft Security Response Center – CVE‑2025‑62562
• Microsoft Security Response Center – CVE‑2025‑64671
• Microsoft Security Response Center – CVE‑2025‑54100
• Microsoft Docs – Windows Update Deployment
• SANS Internet Storm Center – Patch Tuesday Roundup