CVE-2017-5556 in Foxit Reader
Summary
by MITRE
The ConvertToPDF plugin in Foxit Reader before 8.2 and PhantomPDF before 8.2 on Windows, when the gflags app is enabled, allows remote attackers to cause a denial of service (out-of-bounds read and application crash) via a crafted JPEG image. The vulnerability could lead to information disclosure; an attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the current process.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 05/14/2026
The vulnerability identified as CVE-2017-5556 represents a critical security flaw in Foxit Reader and PhantomPDF software versions prior to 8.2 on Windows platforms. This issue specifically affects the ConvertToPDF plugin component that handles JPEG image processing, creating a pathway for remote attackers to exploit system resources through malformed image files. The vulnerability stems from insufficient input validation mechanisms within the plugin's image parsing routines, which fail to properly handle malformed JPEG data structures that could trigger unexpected behavior in the application's memory management systems.
The technical exploitation of this vulnerability manifests through out-of-bounds read conditions that occur when the ConvertToPDF plugin attempts to process specially crafted JPEG images. These malformed images contain data structures that exceed expected boundaries, causing the application to access memory locations outside the allocated buffer regions. The flaw operates at the intersection of memory corruption and input validation failure, creating conditions where the application crashes due to accessing invalid memory addresses while simultaneously potentially exposing sensitive data from adjacent memory regions. This vulnerability maps directly to CWE-125 Out-of-bounds Read and CWE-129 Improper Validation of Array Index, both of which are classified under the broader category of memory safety issues.
From an operational perspective, this vulnerability presents significant risks to organizations relying on Foxit Reader and PhantomPDF for document processing and conversion tasks. The remote attack vector allows adversaries to compromise systems without requiring local access or user interaction beyond viewing the malicious document. The denial of service impact can disrupt business operations through application crashes and system instability, while the potential for information disclosure creates additional security concerns where sensitive data might be exposed through memory leaks. The vulnerability's ability to potentially enable code execution in the context of the current process represents a severe escalation risk that could allow attackers to establish persistent access or escalate privileges within the compromised environment. This aligns with ATT&CK technique T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, demonstrating how initial exploitation can lead to broader system compromise.
Organizations should implement immediate mitigations including updating to Foxit Reader version 8.2 or later and PhantomPDF version 8.2 or later, which contain patched implementations of the ConvertToPDF plugin with enhanced input validation and memory boundary checking. System administrators should also consider implementing network-level restrictions that prevent processing of untrusted PDF documents, particularly when these documents contain embedded JPEG images. Additionally, monitoring for unusual application crashes or memory access patterns can help detect exploitation attempts, while regular security assessments of document processing workflows can identify potential attack vectors. The vulnerability serves as a reminder of the critical importance of input validation in document processing software and highlights the need for robust memory safety mechanisms in applications handling untrusted data sources.