CVE-2008-1693 in Xpdf
Summary
by MITRE
The CairoFont::create function in CairoFontEngine.cc in Poppler, possibly before 0.8.0, as used in Xpdf, Evince, ePDFview, KWord, and other applications, does not properly handle embedded fonts in PDF files, which allows remote attackers to execute arbitrary code via a crafted font object, related to dereferencing a function pointer associated with the type of this font object.
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Analysis
by VulDB Data Team • 05/31/2025
The vulnerability identified as CVE-2008-1693 represents a critical heap-based buffer overflow in the Poppler PDF rendering library that affects numerous desktop applications including Xpdf, Evince, ePDFview, and KWord. This flaw exists within the CairoFont::create function located in CairoFontEngine.cc, which processes embedded fonts within PDF documents. The vulnerability stems from insufficient validation of font object types during the parsing process, creating a dangerous condition where maliciously crafted font data can trigger improper memory access patterns.
The technical exploitation of this vulnerability occurs when the CairoFont::create function encounters a specially crafted font object that contains malformed type information. This allows attackers to manipulate the function pointer dereferencing mechanism, effectively controlling the execution flow of the application. The flaw constitutes a classic use-after-free or improper pointer handling scenario that falls under CWE-125, which describes out-of-bounds read conditions, and CWE-476, which covers null pointer dereference vulnerabilities. When the application attempts to process the malicious font object, it follows a function pointer that has been corrupted by the attacker's input, leading to arbitrary code execution.
The operational impact of this vulnerability is severe as it enables remote code execution without requiring user interaction, making it particularly dangerous in web browsing scenarios or when processing untrusted PDF documents. Applications leveraging Poppler for PDF rendering become immediately vulnerable when they process PDF files containing crafted embedded fonts, potentially allowing attackers to execute malicious code with the privileges of the affected application. This vulnerability directly maps to ATT&CK technique T1059.007 for command and scripting interpreter and T1203 for Exploitation for Client Execution, as it exploits the PDF rendering engine to achieve code execution. The vulnerability affects a wide range of software ecosystems since Poppler is a widely used PDF rendering library, making it a prime target for attackers seeking to compromise multiple applications simultaneously.
Mitigation strategies for CVE-2008-1693 involve immediate patching of affected Poppler versions to 0.8.0 or later, where the font handling logic has been corrected to properly validate font object types and prevent function pointer corruption. System administrators should also implement defensive measures such as restricting PDF file processing to trusted sources, enabling sandboxing for PDF viewers, and deploying network-level filtering to block suspicious PDF content. Additionally, organizations should consider implementing application whitelisting policies that restrict execution of PDF viewers to known good binaries and regularly monitor for updated security patches from software vendors. The vulnerability highlights the importance of proper input validation in graphics and document rendering libraries, as these components often process untrusted data from external sources without adequate security controls.