Microsoft’s December 2025 Patch Tuesday: Addressing 56 Vulnerabilities Including Three Zero-Days
On December 9, 2025, Microsoft released its final Patch Tuesday updates for the year, addressing 56 security vulnerabilities across various products, including Windows, Office, Exchange Server, and others. This comprehensive update is particularly noteworthy due to the inclusion of three zero-day vulnerabilities—two of which were publicly disclosed prior to patch availability, and one that has been actively exploited in the wild.
Breakdown of Vulnerabilities:
The December 2025 Patch Tuesday encompasses a diverse array of security issues:
– Remote Code Execution (RCE) Vulnerabilities: 19 instances
– Elevation of Privilege Vulnerabilities: 28 instances
– Information Disclosure Vulnerabilities: 4 instances
– Denial of Service (DoS) Vulnerabilities: 3 instances
– Spoofing Vulnerabilities: 2 instances
Notably, there are no moderate or low-severity flaws highlighted in this release, underscoring Microsoft’s focus on mitigating high-impact threats.
Zero-Day Vulnerabilities:
Among the addressed vulnerabilities, three zero-day flaws stand out:
1. CVE-2025-62221 – Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability:
– Severity: Important
– Exploitation Status: Actively exploited in the wild
– Description: This use-after-free vulnerability in the Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally, potentially leading to full system compromise.
2. CVE-2025-64671 – GitHub Copilot for JetBrains Remote Code Execution Vulnerability:
– Severity: Important
– Exploitation Status: Publicly known, but exploitation is less likely
– Description: This vulnerability enables command injection through malicious prompts, allowing attackers to execute arbitrary code within the development environment.
3. CVE-2025-54100 – PowerShell Remote Code Execution Vulnerability:
– Severity: Important
– Exploitation Status: Publicly known
– Description: This flaw allows automatic script execution when webpages are retrieved using the `Invoke-WebRequest` cmdlet, potentially leading to unauthorized code execution.
Critical Remote Code Execution Flaws:
Beyond the zero-day vulnerabilities, the update addresses several critical RCE flaws:
– CVE-2025-62554 and CVE-2025-62557 – Microsoft Office RCE Vulnerabilities:
– Severity: Critical
– Description: These vulnerabilities allow remote attackers to execute arbitrary code through malicious documents, posing significant risks in environments where document sharing is routine.
– CVE-2025-62549 – Routing and Remote Access Service (RRAS) RCE Vulnerability:
– Severity: Critical
– Description: This flaw permits network-based code execution without prior authentication, providing attackers with direct pathways into corporate networks.
Affected Products:
The vulnerabilities span a wide range of Microsoft products, including:
– Windows 10, Windows 11, and Windows Server editions
– Microsoft Office applications (Excel, Word, Outlook, Access)
– Hyper-V
– Azure Monitor Agent
– PowerShell
– Third-party tools like GitHub Copilot for JetBrains
Recommendations:
Given the severity and breadth of the vulnerabilities addressed, organizations are urged to prioritize the following actions:
1. Immediate Patching: Deploy the December 2025 Patch Tuesday updates promptly to mitigate the risks associated with these vulnerabilities.
2. Focus on Zero-Days: Pay special attention to systems affected by CVE-2025-62221, CVE-2025-64671, and CVE-2025-54100, given their zero-day status and potential for exploitation.
3. Update Development Environments: For organizations utilizing GitHub Copilot for JetBrains, ensure that the development environment is updated to address CVE-2025-64671.
4. Review PowerShell Usage: Assess and restrict the use of PowerShell scripts, particularly those that retrieve web content, to mitigate the risks associated with CVE-2025-54100.
5. Monitor for Exploitation: Stay vigilant for signs of exploitation, especially concerning the actively exploited CVE-2025-62221, and implement additional security measures as needed.
By taking these proactive steps, organizations can enhance their security posture and protect their systems from potential threats.
