CVE-2025-6659 is a high-severity vulnerability affecting PDF-XChange Editor version 10.5.2.395, specifically within its handling of PRC file parsing. The root cause is an out-of-bounds write (CWE-787) due to improper validation of user-supplied data during the parsing process. This flaw allows an attacker to write data beyond the allocated buffer boundaries, leading to memory corruption. Exploitation requires user interaction, such as opening a maliciously crafted PDF file containing a PRC object or visiting a malicious webpage that triggers the vulnerable parser. Successful exploitation enables remote code execution (RCE) in the context of the current user process, potentially allowing an attacker to execute arbitrary code with the privileges of the user running the PDF-XChange Editor. The vulnerability does not require prior authentication but does require user action to trigger. The CVSS 3.0 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. No known exploits are currently reported in the wild, but the vulnerability is publicly disclosed and could be targeted by attackers in the near future. The lack of a patch at the time of disclosure increases the urgency for mitigation. This vulnerability is significant because PDF-XChange Editor is widely used for PDF viewing and editing, and PRC files are a component of 3D content embedded in PDFs, which may be less commonly scrutinized, potentially allowing stealthy exploitation vectors.

For European organizations, this vulnerability poses a substantial risk due to the widespread use of PDF-XChange Editor in both private and public sectors for document handling. Successful exploitation could lead to remote code execution, enabling attackers to compromise endpoints, steal sensitive data, deploy malware, or move laterally within networks. The impact on confidentiality, integrity, and availability is high, potentially leading to data breaches, disruption of business operations, and loss of trust. Sectors such as finance, government, legal, and healthcare, which heavily rely on PDF documents for communication and record-keeping, are particularly at risk. Additionally, the requirement for user interaction means phishing campaigns or malicious document distribution remain effective attack vectors. Given the lack of known exploits currently, organizations have a window to implement mitigations before widespread exploitation occurs. However, the high severity and ease of exploitation once triggered make this a critical threat to address promptly.

Immediately restrict or monitor the use of PDF-XChange Editor version 10.5.2.395 within the organization until a vendor patch is available. Implement strict email filtering and attachment scanning to detect and block malicious PDFs, especially those containing embedded 3D content or PRC files. Educate users to be cautious when opening PDF files from untrusted or unknown sources, emphasizing the risk of embedded 3D objects. Deploy application whitelisting and endpoint detection and response (EDR) solutions to detect anomalous behavior indicative of exploitation attempts. Use sandboxing or isolated environments for opening PDF files from external sources to contain potential exploitation. Monitor network traffic and endpoint logs for unusual activity that could indicate exploitation attempts or post-exploitation lateral movement. Engage with the vendor to obtain timely patches or workarounds and apply them as soon as they become available. Consider alternative PDF viewers with a lower attack surface for critical environments until this vulnerability is resolved.