CVE-2005-4504 in Mac OS X
Summary
by MITRE
The khtml::RenderTableSection::ensureRows function in KHTMLParser in Apple Mac OS X 10.4.3 and earlier, as used by Safari and TextEdit, allows remote attackers to cause a denial of service (memory consumption and application crash) via HTML files with a large ROWSPAN attribute in a TD tag.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 02/09/2025
The vulnerability identified as CVE-2005-4504 represents a critical denial of service flaw within the KHTML rendering engine component of Apple Mac OS X 10.4.3 and earlier versions. This issue specifically affects applications that utilize the KHTMLParser library, including Safari web browser and TextEdit text processor. The vulnerability stems from inadequate input validation and memory management within the khtml::RenderTableSection::ensureRows function, which processes HTML table structures during document rendering. When malicious HTML content containing excessive ROWSPAN attributes is processed, the function fails to properly handle the memory allocation required for rendering table rows, leading to uncontrolled resource consumption and eventual application instability.
The technical exploitation of this vulnerability occurs through the manipulation of HTML table elements, specifically targeting the ROWSPAN attribute within table data cells. When a web browser or application encounters an HTML file containing a TD tag with an exceptionally large ROWSPAN value, the khtml::RenderTableSection::ensureRows function attempts to allocate memory resources proportional to the specified row span. This process lacks proper bounds checking and memory limitation mechanisms, allowing attackers to craft malicious HTML documents that trigger excessive memory consumption. The flaw operates at the rendering engine level, making it particularly dangerous as it can be exploited through standard web browsing activities without requiring special privileges or user interaction beyond visiting a malicious website.
The operational impact of this vulnerability extends beyond simple application crashes to encompass significant system resource exhaustion and potential service disruption. When exploited, the vulnerability causes applications to consume excessive memory resources, potentially leading to system slowdowns or complete application termination. In the context of Safari browser, this could result in webpage rendering failures and complete browser crashes, while TextEdit applications might become unresponsive when opening malicious documents. The vulnerability's remote exploitation capability means that attackers can deliver malicious HTML content through web servers, email attachments, or other delivery mechanisms without requiring physical access to the target system. This characteristic aligns with attack patterns classified under the MITRE ATT&CK framework's T1203 (Exploitation for Client Execution) and T1499 (Endpoint Denial of Service) techniques.
From a security standards perspective, this vulnerability corresponds to CWE-129, which addresses insufficient input validation, and CWE-770, which covers allocation of resources without limits or throttling. The improper handling of memory allocation in the rendering function demonstrates a classic buffer overflow prevention failure, where the system does not adequately validate or limit the magnitude of resource requests. The vulnerability also reflects broader issues in web browser security architecture, particularly in how rendering engines process malformed HTML content. Mitigation strategies should focus on implementing robust input validation, memory allocation limits, and proper bounds checking within the KHTML rendering engine. System administrators should prioritize updating to patched versions of Mac OS X, while developers should implement defensive programming practices including proper parameter validation and resource management to prevent similar vulnerabilities in future implementations. The vulnerability serves as a reminder of the importance of thorough input validation in rendering engines and the potential for seemingly benign HTML attributes to cause significant system instability.