CVE-2018-1000036 in MuPDF
Summary
by MITRE
In MuPDF 1.12.0 and earlier, multiple memory leaks in the PDF parser allow an attacker to cause a denial of service (memory leak) via a crafted file.
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Analysis
by VulDB Data Team • 07/12/2024
The vulnerability identified as CVE-2018-1000036 represents a critical memory management flaw within the MuPDF document processing library version 1.12.0 and earlier. This issue manifests as multiple memory leaks occurring within the PDF parser component, which is responsible for interpreting and rendering pdf documents. The vulnerability arises from insufficient memory deallocation mechanisms when processing malformed or specially crafted pdf files, leading to progressive memory consumption that can ultimately result in system resource exhaustion.
The technical implementation of this vulnerability stems from inadequate handling of memory allocation and deallocation during pdf parsing operations. When MuPDF encounters certain malformed pdf structures or maliciously constructed pdf files, the parser fails to properly release allocated memory blocks, causing memory leaks to accumulate over time. This flaw operates at the core level of document processing where pdf objects are parsed, interpreted, and stored in memory for rendering. The vulnerability is particularly concerning because it can be triggered through simple file manipulation without requiring complex exploitation techniques, making it accessible to attackers with minimal technical expertise. The memory leaks occur during various parsing phases including object parsing, stream handling, and cross-reference table processing, where allocated memory structures are not consistently freed when processing unexpected pdf constructs.
From an operational impact perspective, this vulnerability creates significant risk for systems relying on MuPDF for pdf document processing and rendering. The memory leak behavior can lead to progressive system degradation, where applications consuming the library gradually consume increasing amounts of system memory until system performance degrades substantially or complete system crashes occur. This denial of service condition affects not only individual applications but can potentially impact entire server environments where multiple processes utilize the vulnerable library. The vulnerability is particularly dangerous in web applications, document processing servers, and mobile applications that frequently process pdf files from untrusted sources. Network-based exploitation becomes possible when attackers can upload or deliver malicious pdf files that trigger the memory leak conditions, potentially allowing them to consume system resources and cause service disruption.
Mitigation strategies for CVE-2018-1000036 primarily involve immediate software updates to versions of MuPDF that address the memory management issues. Organizations should prioritize patching affected systems and applications to prevent exploitation. Additionally, implementing input validation and sanitization measures can help reduce the risk of triggering memory leaks through malformed pdf files. Security monitoring should include detection of unusual memory consumption patterns that may indicate exploitation attempts. The vulnerability aligns with CWE-401, which addresses improper handling of memory allocation and deallocation, and represents a classic denial of service vector that could be classified under ATT&CK technique T1499.004 for network denial of service. System administrators should also consider implementing sandboxing mechanisms and restricting pdf file processing to trusted sources to minimize potential impact from exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of vulnerable MuPDF versions within the organization's infrastructure.