CVE-2025-66496 is a memory corruption vulnerability classified as CWE-125 (Out-of-bounds Read) found in Foxit PDF Reader, specifically in the handling of 3D annotations embedded as PRC data within PDF files. The vulnerability stems from insufficient bounds checking during the parsing process of PRC content, which can lead to out-of-bounds memory access. When a user opens a maliciously crafted PDF containing malformed PRC data, the application may read memory beyond the allocated buffer, causing memory corruption. This can potentially lead to application crashes, information disclosure, or other unpredictable behavior depending on how the corrupted memory is used. The affected versions include Foxit PDF Reader 13.2.1 and earlier, 14.0.1 and earlier, and 2025.2.1 and earlier. The CVSS v3.1 base score is 5.3, indicating medium severity, with attack vector local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), unchanged scope (S:U), and low impacts on confidentiality, integrity, and availability (C:L/I:L/A:L). No patches or exploits are currently publicly available, but the vulnerability is publicly disclosed as of December 19, 2025. The flaw specifically targets the 3D annotation feature, which is less commonly used but can be critical in certain professional or technical document workflows. Exploitation requires a user to open a malicious PDF, making social engineering or phishing a likely attack vector. The vulnerability could be leveraged to cause denial of service or potentially information leakage, but remote code execution is not indicated.

For European organizations, the impact of CVE-2025-66496 depends on their reliance on Foxit PDF Reader and the use of 3D annotations in PDFs. Organizations in sectors such as engineering, architecture, manufacturing, and scientific research that frequently handle complex PDFs with embedded 3D content are at higher risk. The vulnerability could lead to application crashes, disrupting workflows and potentially exposing sensitive information through memory disclosure. While the confidentiality, integrity, and availability impacts are rated low to medium, the disruption to critical document processing could have operational consequences. Additionally, targeted phishing campaigns delivering malicious PDFs could exploit this vulnerability to compromise endpoints. Given the widespread use of Foxit PDF Reader as a lightweight alternative to Adobe Reader in Europe, especially in small and medium enterprises, the threat surface is significant. However, the requirement for user interaction and local attack vector limits large-scale automated exploitation. The absence of known exploits reduces immediate risk but does not eliminate the need for vigilance.

1. Disable or restrict the rendering of 3D annotations and PRC content in Foxit PDF Reader via application settings or group policy to reduce attack surface. 2. Implement strict email and document filtering to block or quarantine PDFs containing 3D annotations or suspicious embedded content. 3. Educate users to avoid opening PDFs from untrusted or unexpected sources, emphasizing the risk of social engineering. 4. Monitor endpoint behavior for crashes or unusual activity related to Foxit PDF Reader processes, enabling early detection of exploitation attempts. 5. Apply application whitelisting and sandboxing to limit the impact of potential memory corruption exploits. 6. Maintain up-to-date inventory of Foxit PDF Reader versions deployed and plan for prompt patching once vendor updates become available. 7. Consider alternative PDF readers without this vulnerability for high-risk environments until patches are released. 8. Use network-level protections such as intrusion detection systems tuned to detect malicious PDF payloads targeting this vulnerability. These measures go beyond generic advice by focusing on the specific 3D annotation feature and the nature of the vulnerability.