CVE-2018-8107 in Xpdf
Summary
by MITRE
The JPXStream::close function in JPXStream.cc in xpdf 4.00 allows attackers to launch denial of service (heap-based buffer over-read and application crash) via a specific pdf file, as demonstrated by pdftohtml.
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Analysis
by VulDB Data Team • 03/07/2025
The vulnerability identified as CVE-2018-8107 resides within the JPXStream::close function in xpdf version 4.00, specifically in the JPXStream.cc source file. This flaw represents a heap-based buffer over-read condition that occurs when processing specially crafted pdf files, making it particularly dangerous for applications that rely on xpdf for pdf processing operations. The vulnerability is triggered during the cleanup phase of JPXStream processing, where the close function attempts to access memory beyond the allocated buffer boundaries, leading to undefined behavior and system instability.
The technical exploitation of this vulnerability occurs when malicious pdf files contain malformed JPX (JPEG 2000) stream data that causes the JPXStream::close function to read beyond the intended buffer limits. This heap-based buffer over-read creates a condition where the application attempts to access memory locations that have not been properly allocated or have already been freed, resulting in memory corruption. The vulnerability is particularly concerning because it can be triggered through legitimate pdf processing operations such as pdftohtml conversion, making it difficult to distinguish between benign and malicious pdf files at runtime.
When exploited, this vulnerability manifests as a denial of service condition that can cause application crashes and system instability. The heap-based buffer over-read can lead to unpredictable application behavior including segmentation faults, memory corruption, and complete application termination. Attackers can leverage this vulnerability by crafting pdf files that contain malicious JPX stream data, which when processed by applications using xpdf libraries, will trigger the buffer over-read condition. The impact extends beyond simple application crashes to potentially enable more sophisticated attacks if combined with other vulnerabilities, as memory corruption can sometimes be exploited to execute arbitrary code.
The operational impact of CVE-2018-8107 is significant for organizations that rely on pdf processing capabilities, particularly those using xpdf-based applications such as pdftohtml, pdfinfo, and other tools that depend on the xpdf library for pdf handling. Systems running affected versions of xpdf are vulnerable to denial of service attacks that can disrupt legitimate pdf processing workflows and potentially provide attackers with a foothold for further exploitation. This vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and can be mapped to ATT&CK technique T1059.007 for execution through command-line interfaces that may be used in pdf processing workflows. Organizations should consider this vulnerability as part of a broader security posture assessment, particularly in environments where pdf processing is a critical function.
Mitigation strategies for CVE-2018-8107 should focus on immediate patching of affected xpdf versions to the latest releases that contain fixes for this buffer over-read condition. System administrators should implement strict pdf file validation and sanitization processes before processing pdf files through xpdf-based applications. Network-level protections such as pdf file filtering and sandboxing mechanisms can help reduce the attack surface by preventing potentially malicious pdf files from reaching vulnerable applications. Additionally, organizations should monitor for any signs of exploitation attempts and implement proper logging and alerting mechanisms to detect unusual pdf processing patterns that might indicate attempted exploitation of this vulnerability. Regular security assessments and vulnerability scanning should include checks for xpdf installations to ensure all systems are running patched versions that address this specific heap-based buffer over-read condition.