CVE-2023-51560 in Foxit
Summary
by MITRE • 05/03/2024
Foxit PDF Reader Annotation Type Confusion Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit PDF Reader. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the handling of Annotation objects. The issue results from the lack of proper validation of user-supplied data, which can result in a type confusion condition. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-22259.
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Analysis
by VulDB Data Team • 08/13/2025
The CVE-2023-51560 vulnerability represents a critical type confusion flaw in Foxit PDF Reader that enables remote code execution through malicious PDF annotation objects. This vulnerability falls under the CWE-704 category of Incorrect Type Conversion or Cast, specifically manifesting as a type confusion condition that occurs when the application fails to properly validate user-supplied data during annotation object processing. The flaw exists within the PDF reader's annotation handling mechanism where insufficient input validation allows attackers to manipulate object types in ways that bypass normal execution flow. This issue demonstrates a classic security weakness in software that processes untrusted binary data, where the application's type checking mechanisms are inadequate to prevent malicious data from being interpreted as different object types than intended.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise when exploited successfully. Attackers can leverage this condition to execute arbitrary code within the context of the Foxit PDF Reader process, potentially leading to privilege escalation or full system compromise depending on the execution environment. The vulnerability requires user interaction to be exploited, meaning that victims must either visit a malicious webpage containing crafted PDF content or open a specially crafted PDF file. This user interaction requirement aligns with ATT&CK technique T1203 - Exploitation for Client Execution, where adversaries rely on social engineering or drive-by attacks to deliver malicious payloads. The type confusion condition creates a predictable execution path where the application's memory management becomes corrupted, allowing attackers to manipulate the program's execution flow and inject malicious instructions.
Security professionals should consider this vulnerability as part of a broader category of memory safety issues that plague PDF processing applications, particularly those handling complex object structures like annotations. The flaw demonstrates how insufficient input validation during object deserialization can lead to severe remote code execution capabilities, making it a prime target for advanced persistent threat actors and cybercriminals. Organizations using Foxit PDF Reader should prioritize immediate patch deployment as recommended by the Zero Day Initiative (ZDI) under CAN-22259, which identified this vulnerability. The mitigation strategy should include not only software updates but also network-level defenses such as web application firewalls and PDF content filtering systems that can detect and block malicious annotation objects. Additionally, user education regarding suspicious PDF files and website visits remains crucial, as the vulnerability's exploitation requires human interaction to succeed. This vulnerability highlights the importance of robust input validation and proper type checking in security-critical applications, particularly those handling complex binary formats like PDF documents where object structures can be manipulated to achieve unintended program behavior.