Microsoft released its final security updates for 2025, addressing at least 56 vulnerabilities across its Windows operating systems and related software. This December Patch Tuesday includes fixes for one zero-day flaw already under active exploitation, alongside two other publicly disclosed vulnerabilities.
Despite a recent trend of fewer monthly security updates, Microsoft resolved a total of 1,129 vulnerabilities throughout 2025. This represents an 11.9% increase compared to 2024. According to Satnam Narang of Tenable, 2025 marks the second consecutive year, and the third time overall, that Microsoft has patched over a thousand vulnerabilities.
The zero-day vulnerability addressed in this update is CVE-2025-62221, a privilege escalation flaw impacting Windows 10 and newer versions. This vulnerability is found within the “Windows Cloud Files Mini Filter Driver,” a system component that allows cloud applications to interact with file system functionalities.
Adam Barnett, a lead software engineer at Rapid7, highlighted the seriousness of this flaw, noting that the mini filter is crucial for services like OneDrive, Google Drive, and iCloud, and remains a core Windows component even if these applications are not installed.
Among the patches, only three vulnerabilities received Microsoft’s “critical” severity rating. These include CVE-2025-62554 and CVE-2025-62557, both affecting Microsoft Office. These can be exploited simply by viewing a malicious email in the Preview Pane. Another critical flaw, CVE-2025-62562, impacts Microsoft Outlook, though Microsoft states the Preview Pane is not an attack vector for this specific issue.
Microsoft also identified several non-critical privilege escalation bugs as being highly likely to be exploited. These include:
- CVE-2025-62458 — Win32k
- 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
Kev Breen, senior director of threat research at Immersive, noted that privilege escalation vulnerabilities are commonly observed in incidents involving host compromises. Breen suggested that while the exact reasons for Microsoft’s “more likely to be exploited” designation are unknown, many of these components have a history of being exploited or possess sufficient technical details from previous CVEs to facilitate weaponization by threat actors. He emphasized the importance of patching these vulnerabilities promptly, even if they are not currently under active exploitation.
A notable vulnerability patched this month is CVE-2025-64671, a remote code execution flaw in the Github Copilot Plugin for Jetbrains. This AI-based coding assistant, used by Microsoft and GitHub, could be exploited to execute arbitrary code by manipulating the large language model (LLM) to bypass a user’s “auto-approve” settings.
CVE-2025-64671 is part of a larger security concern dubbed “IDEsaster” by security researcher Ari Marzuk. This term refers to a systemic crisis within integrated development environments (IDEs), encompassing over 30 vulnerabilities identified across nearly a dozen leading AI coding platforms, including Cursor, Windsurf, Gemini CLI, and Claude Code.
The second publicly disclosed vulnerability patched is CVE-2025-54100, a remote code execution bug in Windows Powershell. This flaw affects Windows Server 2008 and later, allowing an unauthenticated attacker to execute code within the user’s security context.
For a detailed overview of Microsoft’s security updates, the SANS Internet Storm Center provides a comprehensive roundup.
