CVE-2006-4687 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer 5.01 through 6 allows remote attackers to execute arbitrary code via crafted layout combinations involving DIV tags and HTML CSS float properties that trigger memory corruption, aka "HTML Rendering Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 04/27/2026
This vulnerability represents a critical memory corruption flaw in Microsoft Internet Explorer versions 5.01 through 6 that enables remote code execution through carefully crafted HTML content. The vulnerability specifically exploits the browser's handling of layout combinations involving div tags and CSS float properties, creating conditions that lead to memory corruption. According to CWE-125, this falls under the category of "Out-of-bounds Read" where the browser's HTML rendering engine attempts to access memory locations beyond the intended boundaries when processing maliciously constructed CSS float attributes within div elements. The flaw operates at the intersection of HTML parsing and memory management within the browser's rendering engine, creating a pathway for attackers to inject and execute arbitrary code on vulnerable systems.
The technical exploitation occurs when Internet Explorer processes HTML content containing specific combinations of div tags with CSS float properties that cause the browser's memory management to behave unpredictably. This memory corruption can be leveraged by attackers to overwrite critical memory locations, potentially allowing them to execute malicious code with the privileges of the user running the browser. The vulnerability demonstrates characteristics consistent with the ATT&CK technique T1203 - Exploitation for Client Execution, where adversaries exploit software vulnerabilities to execute code on target systems. The memory corruption aspect specifically aligns with ATT&CK tactic T1059 - Command and Scripting Interpreter, as the executed code can include malicious commands or scripts that further compromise the system.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise when attackers successfully exploit it. Organizations running these older versions of Internet Explorer face significant risk as the vulnerability can be triggered through web browsing activities, making it particularly dangerous in enterprise environments where users may encounter malicious content in email attachments, web pages, or corporate websites. The vulnerability's exploitation requires no user interaction beyond visiting a malicious webpage, making it a prime target for drive-by download attacks. Security professionals should note that this vulnerability highlights the importance of maintaining up-to-date software, as Microsoft released patches for this issue in their regular security updates. The memory corruption nature of the flaw also makes it particularly challenging to detect through traditional network monitoring, as the malicious activity may appear as normal browser behavior until the memory corruption actually occurs, which aligns with ATT&CK technique T1566 - Phishing for Information, where the initial compromise often occurs through seemingly legitimate web content.
Organizations should implement immediate mitigations including disabling CSS float properties in corporate browsers, implementing strict web content filtering, and ensuring all systems are updated to supported versions of Internet Explorer or migrated to modern browser platforms. The vulnerability also underscores the need for regular security assessments and penetration testing to identify similar memory corruption vulnerabilities in legacy systems. Additionally, network segmentation and application whitelisting can provide additional defense layers to prevent exploitation of such vulnerabilities. The broader implications of this vulnerability demonstrate how seemingly minor HTML rendering features can create significant security risks when combined with memory management flaws, reinforcing the importance of comprehensive security testing and vulnerability management programs that address both known and emerging threats in web browser environments.