CVE-2016-9430 in w3m
Summary
by MITRE
An issue was discovered in the Tatsuya Kinoshita w3m fork before 0.5.3-31. w3m allows remote attackers to cause a denial of service (segmentation fault and crash) via a crafted HTML page.
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Analysis
by VulDB Data Team • 06/25/2019
The vulnerability identified as CVE-2016-9430 affects the w3m web browser fork developed by Tatsuya Kinoshita, specifically impacting versions prior to 0.5.3-31. This issue represents a critical denial of service vulnerability that can be exploited by remote attackers through the manipulation of HTML content. The vulnerability manifests as a segmentation fault leading to application crashes, effectively rendering the browser unusable for affected users. The w3m browser, known for its lightweight design and text-based interface, is widely used in environments where graphical browsers are not available or desired, making this vulnerability particularly concerning for system administrators and security professionals managing such environments.
The technical flaw underlying CVE-2016-9430 stems from insufficient input validation within the HTML parsing mechanisms of the w3m browser. When processing specially crafted HTML pages, the application fails to properly handle malformed or maliciously constructed elements, causing memory access violations that result in segmentation faults. This type of vulnerability falls under the Common Weakness Enumeration category CWE-125, which describes out-of-bounds read conditions where applications access memory locations beyond the intended buffer boundaries. The flaw likely occurs during the parsing of complex HTML structures or when encountering unexpected element combinations that the parser does not adequately sanitize or validate before processing.
From an operational perspective, this vulnerability creates significant risks for organizations relying on w3m for web browsing in constrained environments such as servers, embedded systems, or terminal-based interfaces. Attackers can exploit this weakness by crafting malicious HTML pages that, when loaded in the vulnerable browser, trigger immediate crashes and system instability. The impact extends beyond simple service disruption as the segmentation faults may cause the browser to terminate unexpectedly, potentially leading to data loss or requiring manual intervention to restore normal operation. In environments where w3m is used for automated tasks or as part of larger systems, such as monitoring tools or automated web scraping applications, this vulnerability could result in cascading failures that affect broader operational capabilities.
The mitigation strategy for CVE-2016-9430 involves immediate upgrading to w3m version 0.5.3-31 or later, which contains the necessary patches to address the HTML parsing vulnerabilities. System administrators should also implement additional security measures such as web content filtering and sandboxing techniques to reduce the attack surface. Organizations using w3m in production environments should conduct thorough testing of the updated version to ensure compatibility with existing workflows and automated processes. The vulnerability demonstrates the importance of maintaining up-to-date software versions and implementing proper input validation mechanisms, aligning with ATT&CK technique T1210 for exploiting vulnerabilities in web browsers and T1499 for denial of service attacks. Regular security assessments and vulnerability scanning should be implemented to identify similar issues in other components of the system infrastructure.