Microsoft December 2025 Patch Tuesday fixes 3 zero-days, 57 flaws

Microsoft's December 2025 Patch Tuesday addresses 57 Microsoft-released flaws (not counting earlier Edge/Mariner fixes), including 28 elevation-of-privilege, 19 remote-code-execution, 4 information-disclosure, 3 denial-of-service and 2 spoofing issues, with three Critical RCEs and three zero-days (one actively exploited). The actively exploited zero-day is CVE-2025-62221 (Windows Cloud Files Mini Filter Driver) which can yield SYSTEM privileges; the two publicly disclosed zero-days are CVE-2025-64671 (GitHub Copilot for JetBrains RCE via cross-prompt injection) and CVE-2025-54100 (PowerShell executing scripts retrieved with Invoke-WebRequest; Microsoft now warns users to use -UseBasicParsing to prevent execution). Institutional IT teams should prioritize immediate patching for the Cloud Files and Office/Outlook critical RCEs, implement the PowerShell mitigation, and factor in additional high-risk updates from Adobe, Fortinet, Google (Android), Ivanti, React (React2Shell ongoing exploitation) and SAP that collectively increase enterprise exposure and operational patching demands.

Analysis

Microsoft's December 2025 Patch Tuesday delivers 57 Microsoft-released fixes (excluding earlier Edge/Mariner patches) comprising 28 elevation-of-privilege, 19 remote-code-execution, 4 information-disclosure, 3 denial-of-service and 2 spoofing vulnerabilities, and includes three Critical RCEs and three zero-days. This release therefore represents a material operational patching burden for enterprise IT teams and tightens short-term security posture requirements across Windows and Office ecosystems.

One zero-day is actively exploited: CVE-2025-62221 in the Windows Cloud Files Mini Filter Driver, which Microsoft says can yield SYSTEM privileges; the two publicly disclosed zero-days are CVE-2025-64671 (GitHub Copilot for JetBrains RCE via cross-prompt injection) and CVE-2025-54100 (PowerShell RCE when using Invoke-WebRequest). Microsoft has implemented a PowerShell warning and recommends the -UseBasicParsing switch as a user mitigation while patches are applied.

Cross-vendor risk increases operational exposure given concurrent high-severity advisories from Adobe, Fortinet, Google (Android), Ivanti, React (React2Shell widespread exploitation) and SAP (9.9 code-injection fix). Market signals in the article point to a cautious/mixed investor stance with modestly negative sentiment for MSFT, FTNT and SAP, implying potential near-term volatility and incremental cybersecurity spend for affected customers.

Key Decisions for Investors

• Monitor Microsoft patch-adoption metrics and customer communications before increasing MSFT exposure given the actively exploited CVE-2025-62221 and the potential for short-term operational disruption
• Avoid initiating large new positions in enterprise software vendors with direct vulnerability exposure (notably SAP) until customers confirm successful patch rollouts and exploit activity subsides