Full Report
Microsoft closed out the year with 1,139 total defects patched, making it the second-largest year in volume behind 2020, according to Trend Micro. The post Microsoft’s last Patch Tuesday of 2025 addresses 57 defects, including one zero-day appeared first on CyberScoop.
Analysis Summary
As requested, here is the summarized vulnerability information in the specified actionable format, focusing on the details extracted from the provided article:
# Vulnerability: Windows Cloud Files Mini Filter Driver Use-After-Free (Zero-Day)
## CVE Details
- CVE ID: CVE-2025-62221
- CVSS Score: 7.8 (High)
- CWE: Use After Free (Implied, based on description)
## Affected Systems
- Products: Windows (Implied: All supported versions)
- Versions: Every supported Windows version.
- Configurations: Not explicitly detailed, but context suggests system-level access is required or implied post-exploitation.
## Vulnerability Description
The vulnerability is a Use-After-Free defect affecting the Windows Cloud Files Mini Filter Driver. Exploitation allows an attacker to perform operations after memory associated with an object has been freed. Microsoft notes this type of bug is often combined with a code execution vulnerability to fully compromise a system.
## Exploitation
- Status: Actively exploited in the wild (Identified as a Zero-Day by the vendor and added to CISA KEV catalog).
- Complexity: Not explicitly stated, but exploitation of a zero-day in the wild suggests **Low to Medium** complexity for targeted adversaries.
- Attack Vector: Likely **Local** or requiring an initial access vector, as the typical outcome is local privilege escalation (gaining system privileges).
## Impact
- Confidentiality: High (System privileges can lead to full system compromise)
- Integrity: High (System privileges can lead to full system compromise)
- Availability: High (System privileges can lead to denial of service or system takeover)
## Remediation
### Patches
- **[Note]:** The specific patch update details are not listed in the article snippet, but patching should be done via the December 2025 Microsoft monthly security update. Verify application of the cumulative update containing the fix for **CVE-2025-62221**.
### Workarounds
- The article mentions the vulnerability appears to affect all supported versions of Windows, and CISA added it to the **Known Exploited Vulnerabilities (KEV) Catalog**. Workaround information is not explicitly provided, but immediate patching is the stated requirement.
## Detection
- **Indicators of Compromise (IOCs):** Not explicitly listed in the summary, but look for suspicious activity involving the Windows Cloud Files Mini Filter Driver (`wcifs.sys`) or attempts to elevate privileges to SYSTEM.
- **Detection Methods and Tools:** Monitoring for exploitation patterns associated with Use-After-Free vulnerabilities, and confirming the application of the December 2025 security updates. CISA’s KEV listing suggests active threat intelligence monitoring should be prioritized.
## References
- Vendor Advisory: [Microsoft’s Security Response Center](https://msrc.microsoft.com/update-guide/releaseNote/2025-Dec) (Defanged link format: `msrc.microsoft.com/update-guide/releaseNote/2025-Dec`)
- CISA KEV: [CISA adds the zero-day to its known exploited vulnerabilities catalog Tuesday](https://www.cisa.gov/news-events/alerts/2025/12/09/cisa-adds-two-known-exploited-vulnerabilities-catalog) (Defanged link format: `cisa.gov/news-events/alerts/2025/12/09/cisa-adds-two-known-exploited-vulnerabilities-catalog`)
- Third Party Analysis: [Trend Micro blog post](https://www.zerodayinitiative.com/blog/2025/12/9/the-december-2025-security-update-review) (Defanged link format: `www.zerodayinitiative.com/blog/2025/12/9/the-december-2025-security-update-review`)
---
*(Note: Other high-severity and noteworthy CVEs identified in the release are listed below for reference, though detailed technical descriptions were not available in the summary text.)*
## Other Noteworthy Vulnerabilities (December 2025 Patch Tuesday)
| CVE ID | Severity | Component | Type/Notes | CVSS | Mitigation Priority |
| :--- | :--- | :--- | :--- | :--- | :--- |
| CVE-2025-62456 | High | Windows Resilient File System | Privilege Escalation/Elevation (High Severity) | 8.8 | High |
| CVE-2025-64678 | High | Windows Resilient File System | Privilege Escalation/Elevation (High Severity) | 8.8 | High |
| CVE-2025-62549 | High | Windows Routing and Remote Access Service | High Severity | 8.8 | High |
| CVE-2025-62550 | High | Azure Monitor Agent | High Severity | 8.8 | High |
| CVE-2025-64672 | High | Microsoft Office SharePoint | High Severity | 8.8 | High |
| CVE-2025-59516 | Flagged | Windows Storage VSP Driver | More likely to be exploited | N/A | Critical (Due to exploitation status) |
| CVE-2025-59517 | Flagged | Windows Storage VSP Driver | More likely to be exploited | N/A | Critical (Due to exploitation status) |
| CVE-2025-62458 | Flagged | Windows Win32K | More likely to be exploited | N/A | Critical (Due to exploitation status) |
| CVE-2025-62470 | Flagged | Windows Common Log File System Driver | More likely to be exploited | N/A | Critical (Due to exploitation status) |
| CVE-2025-62472 | Flagged | Windows Remote Access Connection Manager | More likely to be exploited | N/A | Critical (Due to exploitation status) |