CVE-2025-21367 in Windows
Summary
by MITRE • 02/11/2025
Windows Win32 Kernel Subsystem Elevation of Privilege Vulnerability
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Analysis
by VulDB Data Team • 05/24/2026
This vulnerability exists within the Windows Win32 Kernel Subsystem and represents a critical elevation of privilege flaw that allows attackers to escalate their privileges from standard user level to system level access. The vulnerability stems from improper handling of certain kernel-mode operations that should be restricted to privileged processes only. Attackers can exploit this weakness by crafting malicious code that leverages specific Win32 API calls or kernel objects that are not properly validated before execution. The flaw typically manifests when the kernel subsystem fails to enforce proper access controls or validation checks on user-mode applications attempting to perform privileged operations. This type of vulnerability falls under CWE-264, which specifically addresses permissions, privileges, and access controls in software systems. The attack vector often involves either direct exploitation of kernel objects or indirect manipulation through user-mode components that can trigger kernel-level code execution. According to ATT&CK framework, this vulnerability maps to privilege escalation techniques where adversaries leverage system-level flaws to gain elevated privileges. The operational impact of such a vulnerability is severe as it enables complete system compromise without requiring physical access or advanced exploitation techniques. Once exploited, attackers can execute arbitrary code with kernel-level privileges, allowing them to bypass all operating system security mechanisms, modify system files, install persistent backdoors, and access all user data. The vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it particularly dangerous in enterprise environments where these systems are prevalent. The exploitation typically requires minimal user interaction and can be automated through various attack frameworks. Organizations should immediately apply the relevant security patches provided by Microsoft to address this vulnerability. Additionally, implementing network segmentation, monitoring for unusual privilege escalation attempts, and maintaining up-to-date endpoint protection solutions can help detect and prevent exploitation attempts. System administrators should also review and tighten privilege controls, disable unnecessary user accounts, and implement the principle of least privilege to minimize potential damage from successful exploitation. Regular security assessments and vulnerability scanning should be conducted to identify any unpatched systems within the organization's infrastructure. The underlying technical flaw demonstrates a failure in kernel security model enforcement, specifically in how the subsystem validates and handles privilege checks during kernel transitions. This represents a fundamental breakdown in the operating system's security architecture that requires immediate remediation through official patches and security updates.