CVE-2007-6561 in PDFLib
Summary
by MITRE
Multiple stack-based buffer overflows in PDFLib allow user-assisted remote attackers to execute arbitrary code via a long filename argument to the PDF_load_image function that results in an overflow in the pdc_fsearch_fopen function, and possibly other vectors.
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Analysis
by VulDB Data Team • 04/19/2025
The vulnerability identified as CVE-2007-6561 represents a critical stack-based buffer overflow within the PDFLib library, a widely used component for PDF generation and manipulation in various software applications. This flaw exists in the PDF_load_image function where improper input validation allows attackers to manipulate the filename argument, leading to a buffer overflow condition that can be exploited to execute arbitrary code remotely. The vulnerability specifically manifests when the pdc_fsearch_fopen function processes excessively long filename strings, causing stack corruption that can be leveraged by malicious actors to gain unauthorized system access.
The technical implementation of this vulnerability stems from insufficient bounds checking in the PDFLib library's file handling mechanisms. When a user-provided filename exceeds the allocated buffer space within the pdc_fsearch_fopen function, the excess data overflows into adjacent stack memory locations, potentially overwriting critical program execution data such as return addresses, function pointers, or local variables. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental weakness in software security architecture. The attack vector requires user-assisted remote execution, meaning that an attacker must convince a victim to process a specially crafted PDF document containing malicious filename parameters, typically through social engineering or compromised web content.
The operational impact of CVE-2007-6561 extends beyond simple code execution, as it can lead to complete system compromise when exploited successfully. Attackers can leverage this vulnerability to install malware, modify system files, establish backdoors, or escalate privileges within the affected environment. The vulnerability affects numerous applications that utilize PDFLib for document processing, including content management systems, web applications, and document viewers that may be deployed in enterprise environments. The remote exploitation capability means that attackers can target vulnerable systems without requiring physical access, making this vulnerability particularly dangerous in networked environments where PDF processing occurs automatically.
Mitigation strategies for this vulnerability should include immediate patching of affected PDFLib versions, implementation of input validation controls to limit filename lengths, and deployment of network-based intrusion detection systems to monitor for exploitation attempts. Organizations should also consider implementing application whitelisting policies to restrict execution of untrusted PDF documents and employ sandboxing techniques for PDF processing operations. The vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1203 for Exploitation for Client Execution, as it enables attackers to execute arbitrary commands through compromised applications. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all systems using affected PDFLib versions and establish proper security monitoring procedures to detect potential exploitation attempts in their environments.