CVE-2003-0469 in Windows
Summary
by MITRE
Buffer overflow in the HTML Converter (HTML32.cnv) on various Windows operating systems allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via cut-and-paste operation, as demonstrated in Internet Explorer 5.0 using a long "align" argument in an HR tag.
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Analysis
by VulDB Data Team • 08/13/2025
The vulnerability identified as CVE-2003-0469 represents a critical buffer overflow flaw within the HTML Converter component known as HTML32.cnv that affects multiple Windows operating systems. This vulnerability specifically manifests when processing HTML content through Internet Explorer 5.0, where the system fails to properly validate input parameters during cut-and-paste operations. The flaw resides in the improper handling of the "align" attribute within HR tags, creating a condition where malicious input can exceed the allocated buffer space and overwrite adjacent memory regions.
The technical implementation of this vulnerability follows a classic buffer overflow pattern where the HTML32.cnv component does not perform adequate bounds checking on user-supplied data. When Internet Explorer processes HTML content containing an excessively long "align" argument within an HR tag, the converter attempts to store this data in a fixed-size buffer without proper validation. This allows an attacker to craft malicious HTML content that, when pasted into the browser, triggers the overflow condition. The vulnerability operates at the application level within the HTML rendering engine, specifically targeting the conversion process that transforms HTML markup into displayable content.
From an operational perspective, this vulnerability presents a significant risk to affected systems as it can be exploited to achieve both denial of service and potential code execution capabilities. The remote exploitation nature means attackers can deliver malicious content through web pages or email attachments without requiring local system access. When triggered, the buffer overflow causes Internet Explorer to crash and can potentially allow remote code execution, enabling attackers to gain unauthorized control over affected systems. The impact extends beyond simple service disruption to include complete system compromise, making this a particularly dangerous vulnerability in enterprise environments.
The vulnerability aligns with CWE-121, which describes buffer overflow conditions where data is written beyond the boundaries of a fixed-length buffer. It also corresponds to ATT&CK technique T1059, specifically focusing on command and scripting interpreter execution through browser-based attacks. The attack surface is particularly concerning given that Internet Explorer 5.0 was widely deployed in corporate environments during this period, and the vulnerability could be exploited through social engineering tactics such as phishing emails or compromised websites. Organizations were particularly vulnerable because the attack required no special privileges or local access, making it a highly effective vector for widespread exploitation.
Mitigation strategies for CVE-2003-0469 should include immediate application of vendor security patches, which would address the buffer overflow in the HTML32.cnv component. System administrators should implement network-based protections such as web application firewalls to filter malicious HTML content before it reaches user systems. Browser hardening measures including disabling unnecessary HTML processing features and implementing strict content filtering policies can reduce the attack surface. Additionally, user education regarding the dangers of pasting untrusted content and the implementation of security awareness programs can help prevent successful exploitation attempts. The vulnerability highlights the importance of proper input validation and bounds checking in application development, particularly for components that process user-supplied data in web browsers and document processing applications.