CVE-2011-5046 in Windows
Summary
by MITRE
The Graphics Device Interface (GDI) in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 does not properly validate user-mode input, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via crafted data, as demonstrated by a large height attribute of an IFRAME element rendered by Safari, aka "GDI Access Violation Vulnerability."
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Analysis
by VulDB Data Team • 06/21/2025
The CVE-2011-5046 vulnerability represents a critical kernel-mode memory corruption flaw within Microsoft Windows operating systems that affects multiple versions including XP SP2/SP3, Server 2003 SP2, Vista SP2, Server 2008 SP2/R2/R2 SP1, and Windows 7 Gold/SP1. This vulnerability resides in the Graphics Device Interface component of the win32k.sys kernel-mode driver, which serves as the foundational graphics subsystem for Windows graphical user interfaces. The flaw specifically manifests when the GDI subsystem fails to properly validate user-mode input data, creating a path for malicious code execution through carefully crafted graphical elements. The vulnerability was particularly significant because it could be exploited remotely through web-based attacks, making it a prime target for cybercriminals seeking to compromise Windows systems without physical access.
The technical exploitation of this vulnerability occurs when a malicious actor crafts specially designed HTML content that triggers the flawed GDI validation process. In the specific demonstration mentioned in the CVE description, a large height attribute within an IFRAME element rendered by Safari browser triggers the vulnerability, causing an access violation in the kernel-mode graphics subsystem. This type of flaw falls under the CWE-125 vulnerability category, which describes out-of-bounds read conditions that can lead to memory corruption and arbitrary code execution. The vulnerability exploits the fundamental principle that kernel-mode components should never trust user-mode input data, yet the GDI driver failed to implement proper bounds checking and input sanitization for graphical parameters.
The operational impact of CVE-2011-5046 extends beyond simple privilege escalation to include complete system compromise and potential denial of service conditions. When successfully exploited, attackers can execute arbitrary code with kernel-level privileges, effectively bypassing all Windows security mechanisms including User Access Control, Data Execution Prevention, and Address Space Layout Randomization. This vulnerability directly maps to ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation" and T1059, covering "Command and Scripting Interpreter" as attackers can establish persistent access through the compromised kernel. The vulnerability's remote exploitability makes it particularly dangerous in enterprise environments where users may inadvertently browse malicious websites or receive phishing emails containing crafted HTML content that triggers the vulnerability.
Mitigation strategies for CVE-2011-5046 primarily focus on immediate patch deployment and system hardening measures. Microsoft released security updates that addressed the validation flaw in the GDI subsystem, requiring administrators to apply the relevant Windows updates as soon as possible. Organizations should implement network segmentation and web filtering solutions to prevent access to potentially malicious websites that might contain exploit code. Additionally, deploying exploit protection mechanisms such as Windows Defender Application Control, disabling unnecessary browser plugins, and implementing strict user access controls can significantly reduce the attack surface. The vulnerability highlights the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies, as kernel-mode vulnerabilities like this one provide attackers with the most privileged access possible within the operating system. Security teams should also consider implementing monitoring solutions that can detect anomalous kernel-mode activity patterns that might indicate exploitation attempts, given that this vulnerability can be triggered through legitimate web browsing activities without user interaction.