CVE-2025-66499 is a heap-based buffer overflow vulnerability identified in Foxit PDF Reader, a widely used PDF viewing application. The vulnerability stems from an integer overflow (CWE-190) in the calculation of the image buffer size when parsing JBIG2 image data embedded within PDF files. JBIG2 is a compression format commonly used in scanned documents. When a specially crafted PDF containing malicious JBIG2 data is opened, the integer overflow can cause the buffer size calculation to wrap around, leading to a heap-based buffer overflow. This memory corruption can be exploited by remote attackers to execute arbitrary code within the context of the user running the PDF reader. 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. The CVSS v3.1 base score is 7.8, indicating high severity, with attack vector local (requires the user to open a malicious file), low attack complexity, no privileges required, user interaction required, and high impact on confidentiality, integrity, and availability. No patches were linked at the time of reporting, and no known exploits in the wild have been documented. The vulnerability is critical for environments where untrusted PDFs are handled, as it could lead to remote code execution and full system compromise.

For European organizations, this vulnerability poses a significant risk, particularly for sectors heavily reliant on PDF documents such as finance, legal, government, and healthcare. Successful exploitation could lead to unauthorized access, data theft, disruption of services, or deployment of malware/ransomware. The ability to execute arbitrary code remotely means attackers could gain persistent footholds or move laterally within networks. Given the widespread use of Foxit PDF Reader as an alternative to Adobe Reader, many enterprises and public institutions in Europe may be exposed. The requirement for user interaction (opening a malicious PDF) means phishing or social engineering campaigns could be leveraged to trigger exploitation. The absence of known exploits currently provides a window for proactive mitigation, but the high severity score underscores the urgency. Disruption or compromise of critical infrastructure or sensitive data could have broad regulatory and reputational consequences under GDPR and other European data protection laws.

1. Apply official patches from Foxit Software as soon as they become available to address the integer overflow and buffer overflow issues. 2. Until patches are released, implement strict email and web gateway filtering to block or quarantine suspicious PDF attachments, especially those containing JBIG2 data. 3. Educate users on the risks of opening unsolicited or unexpected PDF files, emphasizing caution with documents from unknown or untrusted sources. 4. Employ endpoint detection and response (EDR) solutions capable of detecting anomalous behaviors related to memory corruption or code execution in PDF readers. 5. Consider disabling or restricting the use of JBIG2 image decoding in Foxit PDF Reader if configurable, or use alternative PDF viewers with no known vulnerabilities. 6. Monitor network and endpoint logs for signs of exploitation attempts or unusual activity related to PDF processing. 7. Implement application whitelisting and sandboxing for PDF readers to limit the impact of potential exploitation. 8. Regularly update all software and maintain an inventory of PDF reader versions deployed across the organization to ensure timely remediation.