CVE-2006-6660 in libkhtml
Summary
by MITRE
The nodeType function in KDE libkhtml 4.2.0 and earlier, as used by Konquerer, KMail, and other programs, allows remote attackers to cause a denial of service (crash) via malformed HTML tags, possibly involving a COL SPAN tag embedded in a RANGE tag.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2006-6660 represents a critical denial of service flaw within the KDE libkhtml library version 4.2.0 and earlier implementations. This vulnerability specifically affects the nodeType function which is integral to HTML parsing and rendering capabilities across multiple KDE applications including Konqueror web browser, KMail email client, and various other programs utilizing the libkhtml framework. The flaw manifests when the system processes malformed HTML content, particularly targeting the interaction between COL SPAN tags and RANGE tags within the HTML document structure.
The technical exploitation of this vulnerability occurs through carefully crafted HTML content that triggers improper handling of node types during the parsing phase. When the nodeType function encounters malformed HTML tags containing embedded COL SPAN elements within RANGE tags, it fails to properly validate or process these structures, leading to memory corruption or stack overflow conditions. This improper handling results in the application crashing and terminating unexpectedly, effectively rendering the affected software unusable for the user. The vulnerability stems from insufficient input validation and error handling within the HTML parsing engine, where the system does not adequately sanitize or reject malformed tag combinations that could lead to buffer overflows or other memory management issues.
The operational impact of this vulnerability extends beyond simple service disruption as it can be leveraged by remote attackers to systematically crash applications used by numerous users across different environments. Since Konqueror and KMail are widely deployed components within KDE desktop environments, this vulnerability affects a substantial user base that relies on these applications for web browsing and email management. The denial of service condition can be triggered through various attack vectors including malicious websites, email attachments, or any HTML content that might be processed by the vulnerable applications, making it particularly dangerous in enterprise and personal computing environments where these applications are frequently used.
This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios that can occur due to improper memory management during parsing operations. The attack pattern follows ATT&CK technique T1499.004 for Denial of Service by Resource Consumption, where the malicious input causes the application to consume excessive resources or crash entirely. The remediation approach requires immediate patching of the libkhtml library to implement proper input validation and error handling for malformed HTML tags, ensuring that the nodeType function properly sanitizes all input before processing. Organizations should also consider implementing HTML content filtering mechanisms and updating their KDE software installations to versions that contain the patched libkhtml library, as the vulnerability affects multiple applications within the KDE ecosystem that share the same underlying parsing engine.