CVE-2010-4398 in Windows
Summary
by MITRE
Stack-based buffer overflow in the RtlQueryRegistryValues function in win32k.sys in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7 allows local users to gain privileges, and bypass the User Account Control (UAC) feature, via a crafted REG_BINARY value for a SystemDefaultEUDCFont registry key, aka "Driver Improper Interaction with Windows Kernel Vulnerability."
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Analysis
by VulDB Data Team • 04/22/2026
The vulnerability described in CVE-2010-4398 represents a critical stack-based buffer overflow affecting the Windows kernel component win32k.sys. This flaw exists within the RtlQueryRegistryValues function and impacts multiple Windows operating systems including XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, as well as Windows 7. The vulnerability stems from improper handling of registry values during kernel-level operations, specifically when processing SystemDefaultEUDCFont registry keys containing crafted REG_BINARY data. The flaw falls under CWE-121 Stack-based Buffer Overflow, which is a fundamental memory safety issue where data written to a buffer exceeds the allocated stack space, potentially corrupting adjacent memory locations.
The technical exploitation of this vulnerability occurs when a local attacker crafts a malicious REG_BINARY value for the SystemDefaultEUDCFont registry key, which then gets processed by the vulnerable RtlQueryRegistryValues function in the win32k.sys driver. During normal operation, this function retrieves registry values to configure system fonts, but the insufficient bounds checking allows an attacker to overwrite adjacent stack memory. The overflow can be leveraged to execute arbitrary code with kernel-level privileges, effectively bypassing the User Account Control feature that was designed to prevent unauthorized privilege escalation. This represents a sophisticated attack vector that combines kernel exploitation with UAC bypass techniques, making it particularly dangerous for system security.
The operational impact of CVE-2010-4398 is severe as it enables local privilege escalation attacks that can fully compromise Windows systems. An attacker with low-privilege access can exploit this vulnerability to gain SYSTEM-level privileges, allowing complete control over the affected system. The bypass of UAC protection mechanisms means that even users with standard accounts can potentially escalate their privileges without triggering system security warnings. This vulnerability was particularly concerning because it affected multiple Windows versions simultaneously, creating a widespread attack surface that could impact enterprise networks and individual workstations alike. The exploitation typically requires local access to the target system, but the privilege escalation aspect makes it extremely valuable to attackers seeking persistent access to compromised machines.
Mitigation strategies for CVE-2010-4398 should include immediate application of Microsoft security updates and patches released in response to this vulnerability. Organizations should ensure that all affected Windows systems are updated with the latest security patches from Microsoft, particularly those addressing kernel-level vulnerabilities in win32k.sys. System administrators should implement comprehensive patch management processes to minimize exposure windows. Additional protective measures include disabling unnecessary registry modifications, implementing strict access controls for registry keys, and monitoring for suspicious registry activity. From an ATT&CK framework perspective, this vulnerability maps to T1068 Privilege Escalation and T1548.002 Bypass User Account Control, highlighting the multi-stage nature of exploitation that combines kernel-level privilege escalation with user interface bypass techniques. Network segmentation and monitoring for unusual registry access patterns can help detect potential exploitation attempts, while regular security assessments should verify that systems remain patched against this and similar vulnerabilities.