CVE-2025-66499 is a heap-based buffer overflow vulnerability identified in Foxit PDF Reader, a widely used PDF viewing application. The flaw stems from an integer overflow (CWE-190) in the calculation of the image buffer size when processing JBIG2 compressed image data embedded within PDF files. Specifically, when Foxit PDF Reader parses specially crafted JBIG2 data, the integer overflow can cause the program to allocate insufficient memory for the image buffer, leading to a heap-based buffer overflow. This memory corruption can be exploited by a remote attacker who crafts a malicious PDF file containing the problematic JBIG2 data. Upon opening or previewing this PDF, the attacker could execute arbitrary code within the context of the user running the application. The vulnerability affects multiple versions of Foxit PDF Reader, including 13.2.1 and earlier, 14.0.1 and earlier, and 2025.2.1 and earlier, indicating a long-standing issue across several releases. The CVSS v3.1 base score is 7.8, with the attack vector classified as local (requiring the user to open a malicious file), low attack complexity, no privileges required, and user interaction necessary. The impact covers confidentiality, integrity, and availability, as arbitrary code execution could lead to data theft, system compromise, or denial of service. No patches or official fixes are currently linked, and no known exploits have been reported in the wild as of the publication date. However, the technical details suggest that once exploit code is developed, it could be leveraged in targeted attacks or malware campaigns. The vulnerability is categorized under CWE-190 (Integer Overflow or Wraparound), emphasizing the root cause in improper handling of integer arithmetic during buffer size calculations. Given the widespread use of Foxit PDF Reader in business and government environments, this vulnerability poses a significant risk if left unmitigated.

For European organizations, the impact of CVE-2025-66499 is considerable due to the extensive use of Foxit PDF Reader in corporate, governmental, and critical infrastructure sectors. Successful exploitation could lead to remote code execution, allowing attackers to gain unauthorized access to sensitive information, manipulate or destroy data, and disrupt operations. This is particularly concerning for sectors handling confidential documents such as finance, healthcare, legal, and public administration. The vulnerability could be exploited via phishing campaigns delivering malicious PDFs, increasing the risk of widespread compromise. Additionally, the ability to execute arbitrary code could facilitate the deployment of ransomware or espionage tools, amplifying the threat to business continuity and data privacy. The requirement for user interaction (opening a malicious PDF) means that social engineering remains a key attack vector. The lack of available patches at the time of disclosure further elevates the risk, as organizations must rely on interim mitigations. Overall, the vulnerability threatens confidentiality, integrity, and availability of systems processing PDF documents, making it a critical concern for European entities reliant on Foxit PDF Reader.

1. Immediate mitigation should include disabling JBIG2 image decoding in Foxit PDF Reader if the option is available, as this directly targets the vulnerable parsing component. 2. Restrict PDF document sources to trusted and verified origins, employing email filtering and endpoint security solutions to block or quarantine suspicious attachments. 3. Educate users about the risks of opening unsolicited or unexpected PDF files, emphasizing caution with attachments from unknown senders. 4. Implement application whitelisting and sandboxing techniques to limit the execution scope of Foxit PDF Reader and contain potential exploitation. 5. Monitor network and endpoint logs for unusual behaviors indicative of exploitation attempts, such as unexpected process spawning or memory corruption alerts. 6. Maintain up-to-date backups and incident response plans to quickly recover from potential compromises. 7. Engage with Foxit Software for updates and patches, applying them promptly once released. 8. Consider deploying alternative PDF readers with no known vulnerabilities to JBIG2 parsing as a temporary measure. 9. Use advanced threat protection tools capable of analyzing and blocking malicious PDF content before reaching end users. These targeted actions go beyond generic advice by focusing on the specific vulnerability vector and operational controls to reduce attack surface and impact.