CVE-2023-51549 in Foxit
Summary
by MITRE • 05/03/2024
Foxit PDF Reader AcroForm Doc Object Use-After-Free 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 Doc objects. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-21867.
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Analysis
by VulDB Data Team • 08/13/2025
The vulnerability identified as CVE-2023-51549 represents a critical use-after-free flaw in Foxit PDF Reader's handling of AcroForm Doc objects, classified under CWE-416. This vulnerability resides in the PDF reader's object management system where insufficient validation occurs before operations are performed on Doc objects, creating a dangerous window where freed memory can be accessed and manipulated. The flaw specifically manifests when the application processes malicious PDF files containing crafted AcroForm elements that trigger improper memory management during object destruction and subsequent reuse. Attackers can exploit this by crafting specially designed PDF documents that, when opened or viewed by an unpatched Foxit PDF Reader, cause the application to free memory associated with Doc objects while simultaneously allowing subsequent operations to reference that freed memory location.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise when exploited successfully. An attacker leveraging CVE-2023-51549 can execute arbitrary code within the context of the Foxit PDF Reader process, which typically runs with the privileges of the user who opened the malicious document. This represents a significant escalation vector as the attacker can potentially gain access to sensitive user data, install malware, or establish persistent backdoors on the compromised system. The requirement for user interaction through visiting a malicious webpage or opening a malicious file aligns with ATT&CK technique T1203, where adversaries leverage legitimate user-facing applications to execute malicious code. The vulnerability's classification as a remote code execution flaw means that attackers can potentially compromise systems without physical access, making it particularly dangerous in enterprise environments where PDF documents are frequently shared and opened by multiple users.
Mitigation strategies for CVE-2023-51549 should focus on immediate patch management and defensive measures to reduce attack surface. Organizations must prioritize updating Foxit PDF Reader to the latest versions that contain fixes for this vulnerability, as the vendor has likely released patches addressing the improper memory management in Doc object handling. Network-level defenses including web application firewalls and content filtering systems can help detect and block malicious PDF files before they reach end users, while email security solutions should be configured to scan PDF attachments for suspicious content patterns. Additionally, implementing user education programs to avoid opening unexpected PDF files from untrusted sources and disabling automatic PDF viewing in web browsers can significantly reduce exploitation risk. The vulnerability's nature makes it particularly suitable for targeted attacks, so organizations should consider implementing endpoint detection and response solutions to monitor for suspicious process behavior and memory access patterns that may indicate exploitation attempts. Security teams should also establish monitoring for unusual PDF processing activities and implement principle of least privilege access controls to limit the potential damage if exploitation occurs.