CVE-2016-9434 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 • 10/05/2022
The vulnerability identified as CVE-2016-9434 affects the w3m web browser fork developed by Tatsuya Kinoshita and represents a significant denial of service weakness that can be exploited remotely by attackers. This issue exists in versions prior to 0.5.3-31 of the software, making it a critical concern for users who have not updated to the patched release. The flaw manifests when the browser encounters a specially crafted HTML page that triggers a segmentation fault, leading to an immediate crash of the application. This type of vulnerability falls under the category of software reliability issues that can severely impact user experience and system availability.
The technical root cause of this vulnerability stems from inadequate input validation and memory management within the w3m browser's HTML parsing engine. When processing maliciously constructed HTML content, the browser fails to properly handle certain malformed elements or sequences that cause the application to attempt invalid memory operations. This results in a segmentation fault that terminates the process abruptly. The vulnerability is classified as a buffer overflow or memory corruption issue that can be exploited through web-based attacks, making it particularly dangerous in environments where users might encounter untrusted content.
From an operational perspective, this vulnerability creates substantial risk for organizations and individuals who rely on w3m for web browsing, particularly in automated or embedded systems where the browser is used to display content without user intervention. The remote exploitation capability means that attackers can trigger crashes simply by hosting malicious content on a web server, without requiring any local interaction from the victim. This makes the vulnerability particularly attractive to threat actors seeking to disrupt services or perform reconnaissance activities. The segmentation fault that occurs upon exploitation can also potentially be leveraged in more sophisticated attacks if combined with other vulnerabilities, though the primary impact remains denial of service.
Security practitioners should note that this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and may also relate to CWE-787, representing out-of-bounds write operations. The attack pattern described in MITRE's ATT&CK framework would fall under the T1499 category for network denial of service, where attackers leverage software flaws to disrupt availability. Organizations using affected versions of w3m should immediately implement patch management procedures to upgrade to version 0.5.3-31 or later. Additionally, network administrators should consider implementing web filtering measures to prevent access to known malicious sites until the software can be properly updated. The vulnerability demonstrates the importance of maintaining up-to-date software in reducing the attack surface and protecting against known exploits that can cause system instability and service disruption.