CVE-2024-49576: Foxit PDF Editor Use-After-Free RCE Flaw

CVE-2024-49576 Overview

A use-after-free vulnerability exists in Foxit Reader 2024.3.0.26795 in the handling of checkbox CBF_Widget objects. When a specially crafted JavaScript code is embedded within a malicious PDF document, it can trigger this vulnerability, leading to memory corruption and potentially arbitrary code execution. This vulnerability requires user interaction—an attacker must trick the user into opening a malicious PDF file. Additionally, exploitation is possible through browser-based attacks if the Foxit Reader browser plugin extension is enabled.

Critical Impact

Successful exploitation allows attackers to execute arbitrary code in the context of the current user, potentially leading to complete system compromise, data theft, or installation of additional malware.

Affected Products

• Foxit PDF Editor (multiple versions)
• Foxit PDF Reader (versions prior to security patch)
• Microsoft Windows (as the underlying operating system)

Discovery Timeline

• 2024-12-18 - CVE-2024-49576 published to NVD
• 2025-08-25 - Last updated in NVD database

Technical Details for CVE-2024-49576

Vulnerability Analysis

This use-after-free vulnerability (CWE-416) occurs within Foxit Reader's JavaScript engine when handling checkbox CBF_Widget objects in PDF documents. Use-after-free vulnerabilities arise when memory that has been freed is subsequently accessed, allowing attackers to potentially control the contents of that memory region. In this case, specially crafted JavaScript embedded in a PDF can manipulate the lifecycle of checkbox widget objects, causing the application to reference memory after it has been deallocated.

The vulnerability can be triggered through two attack vectors: directly opening a malicious PDF file, or visiting a malicious website when the Foxit browser plugin is enabled. Both scenarios require user interaction but can lead to arbitrary code execution with the privileges of the current user.

Root Cause

The root cause is improper memory management in Foxit Reader's handling of CBF_Widget checkbox objects. When JavaScript code manipulates these objects in a specific sequence, it can cause the application to free memory while still maintaining references to it. Subsequent operations on these dangling references allow attackers to corrupt memory structures and hijack program execution flow.

Attack Vector

The attack requires network-based delivery of the malicious payload, either through a crafted PDF file sent via email, download, or file sharing, or through a malicious web page that exploits the browser plugin functionality. While the attack complexity is low, user interaction is required to trigger the vulnerability—the victim must either open the malicious PDF document or navigate to a weaponized website with the Foxit browser plugin active.

The vulnerability allows attackers to potentially achieve complete control over the affected system by corrupting memory and redirecting execution to attacker-controlled code. This can result in data exfiltration, ransomware deployment, or establishing persistent access to the compromised system.

Detection Methods for CVE-2024-49576

Indicators of Compromise

• Unexpected crashes or abnormal behavior in Foxit Reader or Foxit PDF Editor applications
• Presence of PDF files with embedded JavaScript targeting checkbox or form field objects
• Unusual child processes spawned by Foxit Reader applications
• Network connections initiated by Foxit Reader to unknown or suspicious destinations

Detection Strategies

• Monitor for suspicious PDF files containing obfuscated JavaScript code targeting form field manipulation
• Implement endpoint detection rules to identify use-after-free exploitation patterns in memory
• Deploy application behavior monitoring to detect anomalous execution flows from Foxit Reader processes
• Use file sandboxing solutions to analyze PDF attachments before delivery to end users

Monitoring Recommendations

• Enable detailed logging for Foxit Reader application events and crashes
• Monitor for JavaScript execution within PDF documents, especially those manipulating widget objects
• Implement network traffic analysis to detect potential command and control communications following exploitation
• Configure SIEM rules to correlate PDF-related events with subsequent suspicious system activities

How to Mitigate CVE-2024-49576

Immediate Actions Required

• Update Foxit Reader and Foxit PDF Editor to the latest patched versions immediately
• Disable the Foxit browser plugin extension until patching is complete to reduce attack surface
• Configure Foxit Reader to disable JavaScript execution in PDF documents if not required for business operations
• Implement email filtering to quarantine PDF attachments from untrusted sources for analysis

Patch Information

Foxit has addressed this vulnerability in updated versions of their software. Organizations should consult the Talos Intelligence Vulnerability Report for specific version information and apply the latest security updates from Foxit's official distribution channels. Ensure all instances of Foxit PDF Reader and Foxit PDF Editor across the enterprise are updated to remediate this vulnerability.

Workarounds

• Disable JavaScript execution in Foxit Reader via Edit > Preferences > JavaScript > uncheck "Enable JavaScript Actions"
• Remove or disable the Foxit browser plugin from all web browsers to prevent browser-based exploitation
• Implement application whitelisting to prevent unauthorized code execution even if exploitation occurs
• Use alternative PDF readers for handling documents from untrusted sources until patching is complete
• Deploy network segmentation to limit the impact of potential compromise

# Configuration example - Disable JavaScript in Foxit Reader via registry (Windows)
reg add "HKCU\Software\Foxit Software\Foxit Reader\Preferences\Others" /v bEnableJS /t REG_DWORD /d 0 /f

# Verify the setting was applied
reg query "HKCU\Software\Foxit Software\Foxit Reader\Preferences\Others" /v bEnableJS