CVE-2018-8105 in Xpdf
Summary
by MITRE
The JPXStream::fillReadBuf 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-2018-8105 resides within the JPXStream::fillReadBuf function in the JPXStream.cc source file of the xpdf 4.00 library, representing a critical heap-based buffer over-read condition that can be exploited to execute denial of service attacks. This flaw specifically manifests when processing maliciously crafted pdf files, with the exploitation demonstrated through the pdftohtml utility, which is commonly used for converting pdf documents into html format. The vulnerability stems from inadequate bounds checking within the JPXStream class implementation, which handles JPEG2000 image data streams that are often embedded within pdf documents.
The technical implementation of this vulnerability involves the JPXStream::fillReadBuf function failing to properly validate buffer boundaries when reading data from JPEG2000 streams, leading to a scenario where the application attempts to read beyond allocated heap memory regions. This over-read condition occurs during the processing of specific pdf files that contain malformed JPEG2000 data structures, causing the application to access memory locations that are not part of the intended buffer allocation. The flaw is particularly dangerous because it can be triggered by simply opening or processing a malicious pdf document, making it a prevalent vector for denial of service attacks against applications that rely on xpdf for pdf processing capabilities.
The operational impact of CVE-2018-8105 extends beyond simple application crashes, as it can be leveraged by attackers to disrupt services through sustained denial of service attacks. When exploited, the vulnerability causes applications such as pdftohtml to terminate abruptly, effectively rendering them unavailable to legitimate users. This vulnerability affects a wide range of software systems that depend on xpdf for pdf processing, including web applications, document management systems, and content conversion tools. The attack surface is particularly broad given that many pdf processing libraries and applications use xpdf as a foundational component for handling pdf documents.
Security practitioners should note that this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and represents a classic example of heap-based buffer over-read flaws that have been consistently identified in multimedia and document processing libraries. The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for network denial of service, as it enables adversaries to disrupt services through resource exhaustion and application instability. Mitigation strategies should include immediate patching of affected xpdf versions, implementing input validation controls for pdf file processing, and deploying application sandboxing mechanisms to limit the impact of potential exploitation attempts. Organizations should also consider implementing network-based detection rules to identify suspicious pdf file processing activities that may indicate exploitation attempts targeting this vulnerability.