CVE-2016-10221 in MuPDF
Summary
by MITRE
The count_entries function in pdf-layer.c in Artifex Software, Inc. MuPDF 1.10a allows remote attackers to cause a denial of service (stack consumption and application crash) via a crafted PDF document.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 09/16/2024
The vulnerability identified as CVE-2016-10221 resides within the MuPDF document processing library developed by Artifex Software, specifically in the pdf-layer.c component where the count_entries function operates. This flaw represents a classic stack-based buffer overflow condition that can be exploited by remote attackers to execute denial of service attacks against systems processing PDF documents. The vulnerability manifests when the pdf-layer.c module processes malformed PDF files containing crafted layer entries that trigger excessive stack memory consumption during recursive parsing operations.
The technical exploitation of this vulnerability leverages the count_entries function's improper handling of nested or malformed PDF layer structures. When MuPDF encounters a specially crafted PDF document with recursive layer references or excessively deep layer hierarchies, the function's recursive calls consume stack space at an exponential rate. This behavior aligns with CWE-772, which categorizes insufficient resource management as a vulnerability where the system fails to properly control resource allocation and deallocation, leading to exhaustion of available stack memory. The recursive nature of the function call chain creates a stack consumption pattern that can quickly exhaust the available stack space, resulting in application crashes and complete service unavailability.
From an operational perspective, this vulnerability poses significant risks to organizations relying on MuPDF for PDF processing, particularly in web applications, document management systems, and content delivery platforms. The remote exploitation capability means that attackers can trigger the denial of service condition without requiring local access or authentication, making it particularly dangerous in publicly accessible systems. The impact extends beyond simple service disruption as it can affect critical business operations, user experience, and potentially serve as a precursor to more sophisticated attacks that exploit the same underlying memory management flaws. This vulnerability demonstrates the importance of proper input validation and resource management in document processing libraries that handle untrusted content from external sources.
Mitigation strategies for CVE-2016-10221 should prioritize immediate patching of affected MuPDF installations to the latest available versions that contain the fixed count_entries function implementation. Organizations should implement defensive measures such as input sanitization and validation at the application level, limiting the depth of PDF layer processing, and establishing resource limits on stack consumption for PDF processing tasks. Network-level protections including web application firewalls and content filtering systems can help detect and block suspicious PDF files before they reach the processing layer. The vulnerability also highlights the need for regular security assessments of document processing libraries and adherence to secure coding practices that prevent recursive functions from consuming unbounded resources. This case exemplifies ATT&CK technique T1499.004, which involves network denial of service attacks through resource exhaustion, emphasizing the importance of robust resource management in security-critical software components.