CVE-2025-66493 is a use-after-free vulnerability classified under CWE-416, found in the AcroForm handling component of Foxit PDF Reader and Foxit PDF Editor on Windows. The flaw occurs when the software processes specially crafted PDF files containing malicious JavaScript code. Specifically, the vulnerability arises because the application accesses or dereferences a pointer to memory that has already been freed, leading to undefined behavior. This memory corruption can be exploited by remote attackers to execute arbitrary code with the privileges of the user opening the PDF. The vulnerability affects multiple versions of Foxit PDF Editor and Reader, including all versions up to 2025.2.1, 14.0.1, and 13.2.1. The CVSS v3.1 score of 7.8 indicates a high severity, with the attack vector being local (the user must open the malicious file), low attack complexity, no privileges required, but user interaction is necessary. The impact includes potential full compromise of the affected system, with confidentiality, integrity, and availability all at high risk. No public exploits or active exploitation campaigns have been reported yet, but the presence of JavaScript in PDFs and widespread use of Foxit products make this a significant threat. The vulnerability was publicly disclosed on December 19, 2025, with no patch links currently available, suggesting that users should monitor vendor advisories closely. The vulnerability's nature means that attackers could craft PDFs that, when opened, trigger the use-after-free condition, leading to code execution, data theft, or system disruption.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Foxit PDF products in business, government, and critical infrastructure sectors. Successful exploitation could lead to remote code execution, allowing attackers to gain control over affected systems, steal sensitive data, disrupt operations, or deploy ransomware. Sectors heavily reliant on PDF workflows, such as legal, finance, healthcare, and public administration, are particularly vulnerable. The requirement for user interaction (opening a malicious PDF) means phishing campaigns or malicious document distribution could be effective attack vectors. Given the high confidentiality, integrity, and availability impact, exploitation could result in data breaches, operational downtime, and reputational damage. The lack of known exploits in the wild currently provides a window for proactive mitigation, but the high severity score demands urgent attention. European organizations with less mature patch management or endpoint security controls may face elevated risk. Additionally, the vulnerability could be leveraged in targeted attacks against high-value entities or critical infrastructure within Europe.

1. Monitor Foxit Software advisories closely and apply security patches immediately once they become available for the affected versions. 2. Until patches are released, disable or restrict JavaScript execution within Foxit PDF Reader and Editor settings to reduce attack surface. 3. Implement strict email filtering and attachment scanning to detect and block suspicious PDF files containing JavaScript or other embedded code. 4. Educate users on the risks of opening unsolicited or unexpected PDF attachments, emphasizing caution with documents from unknown or untrusted sources. 5. Deploy endpoint detection and response (EDR) solutions capable of identifying anomalous behaviors associated with use-after-free exploitation attempts. 6. Use application whitelisting and sandboxing techniques to limit the impact of potential code execution from compromised PDF readers. 7. Regularly audit and inventory software versions across the organization to ensure vulnerable versions are identified and remediated promptly. 8. Consider network segmentation to isolate critical systems that process sensitive PDF documents, minimizing lateral movement opportunities for attackers.