This month’s Patch Tuesday delivers a modest-sized update, but with high-impact fixes. Microsoft has patched 57 vulnerabilities, including 3 zero-day flaws (one actively exploited and two publicly disclosed) along with several critical-severity bugs.
Here’s a quick breakdown by vulnerability type from this update:
| Vulnerability Type | Count |
|---|---|
| Elevation of Privilege | 28 |
| Remote Code Execution | 19 |
| Information Disclosure | 4 |
| Denial of Service | 3 |
| Spoofing | 3 |
| Total | 57 |
Two vulnerabilities this month were rated Critical (both RCE).
Vulnerability Highlights: Three Zero-Days
CVE-2025-62221: Windows Cloud Files Mini Filter Driver (Elevation of Privilege)
- Overview: A use-after-free bug in the Cloud Files mini-filter driver used for Windows file-sync/placeholder functionality.
- Risk: Local attacker with valid (low-privilege) access can escalate to SYSTEM, allowing full system takeover.
- Exploitation status: Actively exploited in the wild; Microsoft confirmed pre-patch exploitation.
CVE-2025-64671: GitHub Copilot for JetBrains (Command Injection + RCE)
- Overview: A command-injection issue in the GitHub Copilot plugin for JetBrains IDEs that can be triggered via a “cross prompt injection” in untrusted files or MCP servers.
- Risk: Local code/command execution in the user’s environment; dangerous for developer workstations and CI systems that run commands from IDE contexts.
- Exploitation status: Publicly disclosed; Microsoft’s advisory lists it as a publicly disclosed zero-day. No confirmed active exploitation.
CVE-2025-54100: Windows PowerShell (Command Injection + RCE via Invoke-WebRequest parsing)
- Overview: A command-injection/script-execution risk tied to how
Invoke-WebRequestparses web content. Pages with embedded scripts could cause script execution when parsed. - Risk: Remote content retrieved by PowerShell could cause script execution in the user context, relevant for automation and scripted tasks.
- Exploitation status: Publicly disclosed; Microsoft documented the behavior change and recommended using
-UseBasicParsingto avoid script execution. No confirmed active exploitation.
Affected Products & Scope of Update
The December 2025 update impacts a wide range of Microsoft products and components, including but not limited to:
- Core Windows operating system (client and server)
- Windows system drivers (e.g. Cloud Files Mini Filter Driver)
- Windows services such as filter-driver based subsystems
- Microsoft Edge (Chromium-based), part of the month’s broader Edge patch set
Given the diversity of components, from filesystem and kernel drivers to user-space services and browser components, the patch affects desktop, server, cloud, and hybrid environments.
What You Should Do
- Prioritize patching immediately: The active zero-day in the Cloud Files driver represents a high-risk privilege escalation path that’s already exploited.
- Ensure full coverage: Because the flaws span kernels, drivers, and services, patching must cover all Windows installations (clients and servers).
- Audit driver-dependent functionality: Some flaws affect low-level system drivers; organizations should verify that updates don’t disrupt workflows that rely on specialized drivers.
- Check hybrid & cloud environments: Especially for Windows VMs and systems with file-sync or filter-driver dependencies.
- Use defense-in-depth: Patching alone isn’t enough: ensure principle of least privilege, endpoint hardening, and log/alerting for suspicious privilege-escalation attempts.
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