Clement Brako Akomea Table of Contents
Microsoft has released critical security patches addressing an actively exploited zero-day vulnerability in the Windows Kernel, tracked as CVE-2025-62215, as part of its November 2025 Patch Tuesday update.
This privilege escalation flaw has been confirmed as being exploited in the wild by threat actors, making immediate patching a top priority for all Windows administrators and users.
Critical Windows Kernel Vulnerability Exploited in Active Attacks
CVE-2025-62215 is an elevation of privilege (EoP) vulnerability affecting the Windows Kernel, assigned a CVSS score of 7.0 and rated as “Important” severity by Microsoft. The vulnerability was discovered by Microsoft’s own Threat Intelligence Center (MSTIC) and Microsoft Security Response Center (MSRC), who confirmed active exploitation before a patch was made available.
The flaw stems from two interrelated technical weaknesses: a race condition (CWE-362) involving concurrent execution using shared resources with improper synchronization, and a double-free vulnerability (CWE-415) that allows memory corruption.
How the Windows Kernel Zero-Day Works
The vulnerability allows an authenticated attacker with low-level privileges to elevate their access to SYSTEM-level privileges—the highest permission level on Windows systems—by winning a race condition. Once successful, the attacker can corrupt kernel memory through the double-free flaw, enabling complete system takeover.
Race conditions occur when multiple code sequences attempt to access shared resources simultaneously without proper synchronization, violating exclusivity and atomicity principles.
Double-free vulnerabilities happen when memory is freed more than once, leading to heap corruption that attackers can exploit to execute arbitrary code or escalate privileges.
Mike Walters, president and co-founder of Action1, explained that the attack requires local code execution or local access and successful timing of the race condition, which is complex but functional. However, security experts warn that bugs like these are often chained with code execution vulnerabilities by malware to completely compromise systems.
Scope of November 2025 Patch Tuesday Release
Microsoft’s November 2025 Patch Tuesday addresses a total of 63 CVEs, with five rated as Critical and 58 rated as Important. Elevation of privilege vulnerabilities accounted for 46% of the patches, followed by remote code execution (RCE) vulnerabilities at 25.4%.
Additional Critical Vulnerabilities Patched
Beyond CVE-2025-62215, Microsoft addressed several other high-priority security flaws:
CVE-2025-60724 – Windows GDI+ Remote Code Execution
This critical heap-based buffer overflow vulnerability in the Graphics Device Interface Plus (GDI+) component carries a CVSS score of 9.8 and can lead to remote code execution without user interaction.
The vulnerability can be triggered when server-side applications automatically parse specially crafted metafiles, making any system that processes user-supplied documents at risk.
CVE-2025-62199 – Microsoft Office Remote Code Execution
This use-after-free vulnerability in Microsoft Office can be exploited when users download and open malicious files, with the Preview Pane serving as an attack vector. Security researchers note that Preview Pane exploitation increases the probability of real-world attacks since users don’t need to enable dangerous content-simply scrolling through emails in Outlook could be sufficient.
CVE-2025-62222 – Visual Studio Code CoPilot Chat Extension
This vulnerability affects Agentic AI and Visual Studio Code, representing a novel attack chain that targets developers’ trusted environments through prompt injection requiring CoPilot Agent interaction.
Why CVE-2025-62215 Demands Immediate Action
Organizations should treat CVE-2025-62215 as a priority for rapid patching, with special attention to servers, jump hosts, and administrative workstations.
The zero-day status means attackers had access to exploit this vulnerability before defenses were available, and Microsoft has not disclosed specific information about how the flaw was exploited in real-world attacks.
When chained with other vulnerabilities, CVE-2025-62215 becomes a critical threat, potentially enabling server compromise, mass credential exposure, lateral movement, and ransomware deployment.
The flaw is considered a classic post-compromise privilege escalation tool used to deepen control, disable security defenses, and facilitate lateral movement across networks.
Affected Windows Versions and Systems
CVE-2025-62215 affects all currently supported Windows operating system editions and Windows 10 Extended Security Updates (ESU). This marks the first Patch Tuesday since Windows 10 reached end-of-life, meaning only individuals or organizations subscribed to Extended Security Updates can still receive patches for the legacy OS.
The vulnerability impacts:
- Windows 11 (all versions)
- Windows Server 2022 and newer
- Windows 10 (with Extended Security Updates)
- All currently supported Windows Server versions
Technical Details: Understanding the Vulnerability
Race Condition (CWE-362)
The race condition in CVE-2025-62215 involves improper synchronization when multiple threads or processes attempt to access shared kernel resources simultaneously.
Attackers must precisely time their malicious operations to occur between when the kernel checks a resource’s state and when it uses that resource, a classic Time-of-Check-Time-of-Use (TOCTOU) vulnerability.
Double Free (CWE-415)
The double-free component causes a kernel memory allocation to be released twice, corrupting the heap structure. This corruption can be leveraged to overwrite critical data structures, redirect code execution, or bypass security mechanisms.
When exploited successfully, the race condition allows a kernel allocation to be freed twice, leading to heap corruption that grants SYSTEM privileges to the attacker.
Mitigation Strategies and Recommendations
Immediate Actions
- Deploy Security Updates Immediately: CVE-2025-62215 should be at the top of prioritization lists for patching. Apply Microsoft’s November 2025 security updates across all Windows systems without delay.
- Prioritize Critical Systems: Focus initial patching efforts on:
- Domain controllers and authentication servers
- Administrative workstations
- Jump hosts and privileged access workstations
- Internet-facing Windows servers
- Systems processing sensitive data
- Monitor for Exploitation Indicators: Implement detection rules to identify potential exploitation attempts, including:
- Unusual privilege escalation events
- Unexpected SYSTEM-level process creation
- Anomalous kernel-mode activity
- Suspicious memory allocation patterns
Additional Security Measures
Security experts recommend considering disabling the Preview Pane in Microsoft Office until related vulnerabilities are thoroughly addressed. For CVE-2025-60724, organizations should prioritize patching systems that process user-supplied documents, as any public-facing web application that handles file uploads is at risk.
Industry Expert Perspectives
Dustin Childs, head of threat awareness at Trend Micro’s Zero Day Initiative, noted that the race condition demonstrates that some race conditions are more reliable than others for exploitation.
Adam Barnett, lead software engineer at Rapid7, commented that while the GDI+ vulnerability likely isn’t wormable, it’s clearly very serious and should be a top priority for most organizations.
Ben McCarthy, lead cybersecurity engineer at Immersive, emphasized that an attacker with low-privilege local access can run a specially crafted application that repeatedly attempts to trigger the race condition.
Historical Context: Windows Kernel Vulnerabilities in 2025
Including CVE-2025-62215, there have been 11 elevation of privilege vulnerabilities patched in the Windows Kernel in 2025, with five of these being actively exploited zero-days. The cumulative total of CVEs addressed by Microsoft in 2025 has reached 1,084, not counting numerous updates for Azure Linux and CBL Mariner.
Conclusion: Act Now to Protect Windows Systems
The active exploitation of CVE-2025-62215 underscores the ongoing targeting of Windows kernel vulnerabilities by sophisticated threat actors. Microsoft’s exploitability index lists “Exploitation Detected” for this vulnerability, indicating confirmed real-world usage despite the absence of public disclosure of attack details.
Organizations must prioritize deploying Microsoft’s November 2025 security updates immediately, particularly for systems that handle sensitive data or provide privileged access.
The combination of active exploitation, SYSTEM-level privilege escalation, and the potential for chaining with other vulnerabilities makes CVE-2025-62215 one of the most critical Windows security issues of late 2025.
System administrators should:
- Apply the November 2025 Patch Tuesday updates immediately
- Review security logs for potential compromise indicators
- Implement additional monitoring for privilege escalation attempts
- Consider the full scope of 63 vulnerabilities addressed in this release
- Plan for the Windows 10 end-of-life transition if not already on Extended Security Updates
For detailed technical information and the complete list of patches, visit the Microsoft Security Response Center and review your organization’s patch management policies to ensure rapid deployment of critical security updates.
