CVE-2005-2097 in kpdf
Summary
by MITRE
xpdf and kpdf do not properly validate the "loca" table in PDF files, which allows local users to cause a denial of service (disk consumption and hang) via a PDF file with a "broken" loca table, which causes a large temporary file to be created when xpdf attempts to reconstruct the information.
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Analysis
by VulDB Data Team • 06/30/2025
The vulnerability identified as CVE-2005-2097 represents a critical flaw in the xpdf and kpdf PDF rendering libraries that has significant implications for system stability and resource management. This issue affects the parsing of font data within PDF documents, specifically targeting the "loca" table which is part of the OpenType font format used in PDF files. The vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize or verify the integrity of font table structures during PDF processing.
The technical implementation of this vulnerability occurs when xpdf and kpdf attempt to process PDF files containing malformed "loca" tables that contain invalid or excessive data. The flaw manifests in the font reconstruction algorithms that are designed to rebuild font information from the corrupted table structure. When these libraries encounter such malformed data, they attempt to create temporary files with excessively large sizes to accommodate the reconstructed font data, leading to significant disk space consumption and system resource exhaustion.
This vulnerability operates under the broader category of buffer overflows and memory corruption issues, specifically aligning with CWE-129 and CWE-787 which address improper validation of input data. The attack vector is particularly insidious because it can be triggered through simple document viewing operations, making it accessible to local users without requiring specialized privileges or network access. The impact extends beyond simple denial of service to potentially compromise system stability and availability, as the excessive disk space consumption can lead to system crashes or complete unresponsiveness.
The operational impact of CVE-2005-2097 is particularly severe in environments where PDF processing is frequent or automated, such as web servers, document management systems, or email gateways that process PDF attachments. The vulnerability creates a resource exhaustion scenario where temporary files can grow to consume entire disk partitions, leading to system hangs and complete service disruption. This makes it a prime target for resource exhaustion attacks and can be exploited to create persistent denial of service conditions that are difficult to detect and remediate.
Security professionals should implement immediate mitigations including updating to patched versions of xpdf and kpdf libraries, implementing input validation controls for PDF processing systems, and deploying monitoring solutions to detect unusual disk space consumption patterns. The vulnerability also highlights the importance of robust input validation and error handling in font processing libraries, as outlined in the ATT&CK framework under defensive techniques for input validation and resource management. Organizations should consider implementing sandboxing mechanisms for PDF processing and establishing automated alerts for disk space anomalies that could indicate exploitation attempts.