CVE-2016-9629 in w3m
Summary
by MITRE
An issue was discovered in the Tatsuya Kinoshita w3m fork before 0.5.3-33. 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 • 09/16/2024
The vulnerability identified as CVE-2016-9629 represents a critical denial of service flaw within the w3m web browser implementation developed by Tatsuya Kinoshita. This issue affects versions prior to 0.5.3-33 and demonstrates how seemingly benign web content can be weaponized to disrupt system operations. The w3m browser, known for its text-based interface and lightweight design, is widely used in environments where graphical browsers are impractical or undesirable, making this vulnerability particularly concerning for system administrators and security professionals who rely on such tools for remote access and terminal-based browsing.
The technical root cause of this vulnerability lies in inadequate input validation and memory handling within the w3m rendering engine. When processing specially crafted HTML content, the browser fails to properly manage memory allocation and processing flow, resulting in segmentation faults that cause the application to crash abruptly. This behavior maps directly to CWE-125, which describes out-of-bounds read vulnerabilities, and CWE-119, which encompasses improper access to memory locations. The flaw specifically manifests when the browser encounters malformed HTML structures that trigger buffer overflows or invalid memory references during the parsing and rendering process, causing the segmentation fault that terminates the application.
From an operational perspective, this vulnerability presents significant risks for organizations that depend on w3m for secure remote access or terminal-based browsing environments. Attackers can exploit this weakness by crafting malicious HTML pages that, when loaded in the affected browser, will cause immediate application termination. This denial of service condition can be particularly disruptive in environments where w3m serves as the primary browsing tool for system administrators, network operators, or security professionals who rely on text-based interfaces for remote system management. The attack vector is particularly concerning as it requires no authentication or elevated privileges, making it accessible to any remote attacker who can deliver malicious content to a target system.
The impact of this vulnerability extends beyond simple service disruption to potentially compromise operational continuity in critical infrastructure environments. System administrators who depend on w3m for remote access may find their ability to manage systems compromised when attackers exploit this flaw. The vulnerability also aligns with ATT&CK technique T1499.004, which describes network denial of service attacks, and T1566.002, which involves spearphishing with social engineering. Organizations should consider implementing network segmentation and content filtering measures to prevent access to potentially malicious HTML content. Additionally, the vulnerability highlights the importance of keeping text-based browser implementations up to date with security patches, as the issue was resolved in version 0.5.3-33 of the w3m fork. Organizations should also consider alternative browsing solutions or implement additional security controls when using w3m in production environments where security is a primary concern.