CVE-2020-1245 in Windows
Summary
by MITRE
<p>An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory. An attacker who successfully exploited this vulnerability could run arbitrary code in kernel mode. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.</p> <p>To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and take control of an affected system.</p> <p>The update addresses this vulnerability by correcting how Win32k handles objects in memory.</p>
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Analysis
by VulDB Data Team • 02/24/2026
The vulnerability identified as CVE-2020-1245 represents a critical elevation of privilege flaw within the Windows operating system, specifically within the Win32k.sys kernel-mode component. This component serves as a crucial interface between user-mode applications and kernel-mode services, handling graphical user interface objects and system calls. The flaw manifests when Win32k fails to properly validate and manage memory objects during certain operations, creating a pathway for malicious code execution at the highest privilege level. This vulnerability falls under the Common Weakness Enumeration category CWE-121, which deals with stack-based buffer overflow conditions, though the specific implementation involves improper memory handling in kernel components. The security implications are severe as exploitation allows attackers to execute code with kernel-level privileges, effectively bypassing all user-mode security controls and protections.
The exploitation scenario requires initial system access through a valid user account, as the vulnerability cannot be triggered remotely without prior authentication. Attackers must then execute a specially crafted application that leverages the memory handling flaw within Win32k.sys to gain kernel-mode execution. This approach aligns with ATT&CK technique T1068, which describes the use of local privilege escalation techniques to gain system-level access. Once successfully exploited, the malicious code operates with complete system privileges, enabling attackers to install persistent malware, modify or delete critical system files, alter user accounts with administrative rights, and establish backdoors for continued access. The vulnerability's kernel-level nature means that traditional user-mode defenses become ineffective, as the attacker has direct access to system resources and can manipulate the operating system's core functionality.
The operational impact of CVE-2020-1245 extends beyond immediate system compromise, as it provides attackers with persistent access to enterprise networks and critical infrastructure. Organizations running affected Windows versions face significant risk of data breaches, system corruption, and unauthorized access to sensitive information. The vulnerability affects multiple Windows versions including Windows 10, Windows Server 2016, and Windows Server 2019, making it particularly concerning for enterprise environments where these systems are prevalent. Security teams must consider this vulnerability as part of broader attack surface management, as it can serve as a foundation for more sophisticated attacks including lateral movement, credential theft, and data exfiltration. The flaw's persistence across multiple Windows releases indicates a fundamental design issue in how the Win32k component manages memory objects, requiring comprehensive patch management strategies and system hardening measures.
Microsoft's official fix for CVE-2020-1245 addresses the root cause by implementing proper validation mechanisms for memory objects handled by Win32k.sys during system operations. The patch enhances the component's object handling routines to prevent improper memory manipulation that previously enabled kernel-mode code execution. Organizations should prioritize deployment of this security update across all affected systems, particularly those with high-value assets or critical infrastructure. Additional mitigations include implementing application whitelisting policies, disabling unnecessary user accounts, and monitoring for suspicious system activity that might indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of kernel-level security and the need for continuous vulnerability assessment of core operating system components. Security professionals should also consider implementing behavioral monitoring solutions that can detect anomalous kernel-mode activities indicative of privilege escalation attempts, as traditional signature-based detection may not be sufficient to identify exploitation of such complex vulnerabilities.