Microsoft and Adobe Release December Patches for Over 190 Vulnerabilities
Microsoft and Adobe Patch Over 190 CVEs in Final 2025 Update, Including Actively Exploited Windows Zero-Day
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Executive Summary
Microsoft and Adobe have released their final security bulletins for 2025, collectively patching more than 190 vulnerabilities. The updates, released on December 28, 2025, address numerous critical flaws across their product ecosystems. Of particular concern is CVE-2025-62221, a privilege escalation vulnerability in the Microsoft Windows Cloud Files Mini Filter Driver, which Microsoft has confirmed is being actively exploited in the wild. This zero-day threat allows an attacker who has already gained a foothold to elevate their privileges to full system compromise. Adobe's patches cover 139 CVEs in widely used products like Adobe Reader and ColdFusion. Given the scale of the updates and the presence of an exploited zero-day, immediate patch deployment is critical for all organizations.
Vulnerabilities Addressed
Microsoft
Microsoft's update addressed 56 unique CVEs, with the following key highlights:
- CVE-2025-62221 (Zero-Day): An Elevation of Privilege vulnerability in the Windows Cloud Files Mini Filter Driver. An attacker who successfully exploits this could gain SYSTEM privileges. This flaw is confirmed to be under active exploitation.
- Critical Vulnerabilities: Three of the 56 flaws were rated as Critical, involving potential remote code execution.
- Microsoft Office Preview Pane Vector: Multiple vulnerabilities were fixed where the Preview Pane in Outlook and other Office applications could be used as an attack vector, allowing for code execution without user interaction beyond previewing a malicious file.
Adobe
Adobe's release was significantly larger, with five bulletins addressing 139 CVEs:
- Affected Products: Adobe Reader, ColdFusion, Experience Manager, and the Creative Cloud Desktop application.
- Critical Flaws: The updates included fixes for critical vulnerabilities that could lead to arbitrary code execution.
- Adobe Experience Manager: A large number of the fixed vulnerabilities were cross-site scripting (XSS) issues within Adobe Experience Manager, which could be used for session hijacking and other attacks.
Affected Products
- Microsoft: Windows (all versions), Microsoft Office, Azure, Visual Studio, GitHub Copilot.
- Adobe: Adobe Reader, Adobe ColdFusion, Adobe Experience Manager, Adobe Creative Cloud Desktop.
Impact Assessment
The active exploitation of CVE-2025-62221 makes this patch cycle particularly urgent. An attacker could chain this privilege escalation flaw with a separate code execution vulnerability (e.g., from a malicious document or browser exploit) to achieve a full system takeover. For organizations that have not yet patched, this represents a significant risk of compromise.
The large number of vulnerabilities in Adobe products, especially the critical ones in Reader and ColdFusion, also poses a substantial threat. Adobe Reader is ubiquitous, making it a prime target for client-side attacks, while vulnerabilities in server-side products like ColdFusion can lead to direct server compromise and data breaches.
Deployment Priority
Patching should be prioritized based on risk:
- Critical Priority (Deploy Immediately): All Windows workstations and servers should be patched for CVE-2025-62221 due to its active exploitation. Internet-facing systems running vulnerable Adobe products (e.g., ColdFusion servers) should also be patched immediately.
- High Priority (Deploy within 72 hours): All systems with Adobe Reader installed, as well as workstations with Microsoft Office, to address the Preview Pane and other critical RCE vulnerabilities.
- Medium Priority (Deploy within standard patch cycle): The remaining vulnerabilities, including the numerous XSS flaws in Adobe Experience Manager, should be deployed as part of the next scheduled maintenance window.
Cyber Observables
To hunt for pre-patch exploitation of CVE-2025-62221, security teams can look for:
| Type | Value | Description |
|---|---|---|
| event_id | 4688 |
Windows Security Event ID for Process Creation. Monitor for unusual processes being spawned by low-privilege services. |
| process_name | cldflt.sys |
The driver associated with the vulnerability. Monitor for anomalous behavior or crashes related to this driver. |
| log_source | Windows System and Security Event Logs | Look for unexpected privilege escalation events or system errors that could indicate failed exploit attempts. |
Remediation Steps
- Apply Updates: The primary remediation is to apply the security updates provided by Microsoft and Adobe via their standard distribution channels (Windows Update, Adobe Update Manager).
- Verify Installation: After deployment, verify that the patches have been successfully installed on all target systems.
- Workarounds: For the Microsoft Office Preview Pane vulnerabilities, disabling the Preview Pane in Outlook and Windows Explorer can serve as a temporary mitigation until patches are applied. This prevents the exploit from triggering automatically.
Given the active exploitation, organizations should assume that attackers are already scanning for and targeting unpatched systems. Delaying these updates significantly increases the risk of compromise.
Timeline of Events
MITRE ATT&CK Mitigations
Update Software
The primary and most effective mitigation is to apply the security updates provided by Microsoft and Adobe.
Behavior Prevention on Endpoint
EDR solutions can detect and block the exploitation of privilege escalation vulnerabilities by monitoring for suspicious process behaviors.
Software Configuration
Disabling the Preview Pane in Microsoft Office and Windows Explorer can mitigate the risk from Preview Pane-based attack vectors.
D3FEND Defensive Countermeasures
The definitive countermeasure for the threats detailed in the December 2025 Microsoft and Adobe releases is the prompt application of all relevant security patches. Due to the active exploitation of the Windows zero-day, CVE-2025-62221, patching Windows systems should be treated as an emergency action. Organizations must leverage automated patch management systems to deploy these updates across all endpoints and servers. The process should not be considered complete until deployment is verified across 100% of the asset inventory. For the 139 Adobe vulnerabilities, a risk-based approach should be taken, prioritizing patches for Adobe Reader and any internet-facing ColdFusion servers.
To detect potential exploitation of the privilege escalation zero-day (CVE-2025-62221) on unpatched systems, security teams should use EDR tools for advanced process analysis. Detections should focus on identifying anomalous process chains. For example, a rule should be created to alert when a process running with low or medium integrity (like a browser or Office application) spawns a child process that subsequently achieves SYSTEM-level privileges. Monitoring for any process interacting with the cldflt.sys driver and then attempting to access sensitive processes like lsass.exe is another high-fidelity detection strategy. This behavioral approach can catch the exploit in action, even without a specific signature.
As a compensating control for the Microsoft Office vulnerabilities, organizations can use application configuration hardening to reduce the attack surface. Specifically, disabling the Preview Pane in both Microsoft Outlook and Windows Explorer via Group Policy (GPO) can mitigate the risk of zero-click exploits. This prevents the vulnerable code from being rendered automatically when a user simply selects a malicious file. While not a substitute for patching, this is a powerful temporary measure that can be deployed quickly to protect users while the patch is being tested and rolled out, directly addressing the attack vector mentioned in the reports.
Sources & References
Article Author
Jason Gomes
• Cybersecurity PractitionerCybersecurity professional with over 10 years of specialized experience in security operations, threat intelligence, incident response, and security automation. Expertise spans SOAR/XSOAR orchestration, threat intelligence platforms, SIEM/UEBA analytics, and building cyber fusion centers. Background includes technical enablement, solution architecture for enterprise and government clients, and implementing security automation workflows across IR, TIP, and SOC use cases.
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