CVE-2018-5296 in PoDoFo
Summary
by MITRE
In PoDoFo 0.9.5, there is an uncontrolled memory allocation in the PdfParser::ReadXRefSubsection function (base/PdfParser.cpp). Remote attackers could leverage this vulnerability to cause a denial-of-service via a crafted pdf file.
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Analysis
by VulDB Data Team • 12/20/2019
The vulnerability identified as CVE-2018-5296 represents a critical memory management flaw within the PoDoFo PDF processing library version 0.9.5. This issue manifests in the PdfParser::ReadXRefSubsection function located in the base/PdfParser.cpp file, where the library fails to properly validate memory allocation requests during PDF parsing operations. The flaw stems from an uncontrolled memory allocation pattern that allows attackers to manipulate the parsing process through carefully crafted malicious PDF files, potentially leading to system resource exhaustion and service disruption.
The technical nature of this vulnerability aligns with CWE-770, which describes the allocation of resources without proper limits or controls, and can be classified under the ATT&CK technique T1499.1 for resource exhaustion attacks. When a malicious PDF file is processed by the vulnerable PoDoFo library, the PdfParser::ReadXRefSubsection function attempts to allocate memory based on data extracted from the PDF's cross-reference subsection without adequate validation of the allocation parameters. This lack of bounds checking allows an attacker to craft PDF files that trigger excessive memory consumption, causing the application to either crash or become unresponsive due to memory exhaustion.
The operational impact of this vulnerability extends beyond simple denial-of-service conditions, as it affects any application or system that relies on PoDoFo for PDF processing capabilities. Systems utilizing this library for document handling, web applications serving PDF content, or any service that parses user-uploaded PDF files become vulnerable to exploitation. The remote attack vector means that adversaries can trigger this vulnerability without requiring local access, making it particularly dangerous in web-facing applications. The vulnerability can be exploited through various attack scenarios including email attachments, file upload interfaces, and web-based PDF viewers, potentially affecting thousands of systems that depend on the affected library version.
Mitigation strategies for CVE-2018-5296 should prioritize immediate patching of the PoDoFo library to version 0.9.6 or later, where the memory allocation controls have been properly implemented. Organizations should also implement defensive measures such as PDF file validation, size limits for uploaded documents, and sandboxed processing environments to contain potential exploitation attempts. Additionally, network-based intrusion detection systems should be configured to monitor for suspicious PDF file patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper resource management in parsing libraries and highlights the need for robust input validation and memory allocation controls in security-sensitive applications.