CVE-2018-8100 in Xpdf
Summary
by MITRE
The JPXStream::readTilePart function in JPXStream.cc in xpdf 4.00 allows attackers to launch denial of service (heap-based buffer overflow and application crash) or possibly have unspecified other impact 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-2018-8100 resides within the JPXStream::readTilePart function located in JPXStream.cc of the xpdf 4.00 library. This flaw represents a heap-based buffer overflow that occurs when processing specific PDF files, particularly those containing JPX (JPEG 2000) encoded data streams. The vulnerability manifests during the execution of pdftohtml utility which leverages the xpdf library for PDF processing. The flaw stems from inadequate bounds checking when reading tile parts from JPEG 2000 streams, allowing maliciously crafted PDF files to trigger memory corruption through improper handling of data structures.
The technical implementation of this vulnerability involves the improper management of heap memory allocation during JPEG 2000 decompression operations. When the JPXStream::readTilePart function processes tile data, it fails to validate the size parameters of incoming data segments, leading to writes beyond allocated buffer boundaries. This condition creates a heap-based buffer overflow that can result in application crashes, denial of service conditions, or potentially more severe consequences depending on the execution context. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, though the heap-based nature makes it particularly challenging to detect and exploit predictably.
The operational impact of CVE-2018-8100 extends beyond simple denial of service scenarios, as it can be exploited by attackers to disrupt legitimate PDF processing operations across various applications that depend on the xpdf library. Systems utilizing pdftohtml, PDF viewers, or document processing pipelines become vulnerable to crashes and potential service interruptions when encountering maliciously crafted PDF files. This vulnerability particularly affects environments where automated PDF processing occurs, such as web applications, document management systems, and content delivery platforms. The exploitability of this vulnerability is enhanced by the fact that PDF files are commonly used in email attachments, web downloads, and document sharing scenarios, providing multiple attack vectors for exploitation.
Mitigation strategies for CVE-2018-8100 should prioritize immediate patching of affected xpdf versions, with the recommended approach being the upgrade to xpdf 4.01 or later versions that contain the necessary fixes. Organizations should implement defensive measures including PDF file validation and sanitization processes before processing, particularly in environments where untrusted PDF files are encountered. Network-level protections such as PDF content filtering and sandboxing mechanisms can provide additional layers of defense against exploitation attempts. Security monitoring should focus on detecting unusual application crashes or memory allocation patterns during PDF processing operations. The vulnerability aligns with ATT&CK technique T1203 (Exploitation for Client Execution) and T1499 (Endpoint Denial of Service) when leveraged for denial of service attacks. System administrators should also consider implementing access controls and limiting the scope of PDF processing to trusted sources, while maintaining regular security updates to prevent similar vulnerabilities from being exploited in the future.