CVE-2025-6657 is an out-of-bounds read vulnerability identified in PDF-XChange Editor version 10.5.2.395, specifically within the PRC file parsing component. The vulnerability arises due to improper validation of user-supplied data during the parsing process, which can cause the application to read beyond the allocated buffer boundaries. This flaw is classified under CWE-125 (Out-of-bounds Read). Exploitation requires user interaction, such as opening a maliciously crafted PDF file containing a PRC object or visiting a malicious web page that triggers the vulnerability. While the immediate impact is information disclosure—potentially leaking sensitive data from the process memory—this vulnerability can be chained with other exploits to achieve arbitrary code execution within the context of the affected process. The CVSS v3.0 base score is 3.3, indicating a low severity primarily due to the requirement for local access (AV:L), low complexity (AC:L), no privileges required (PR:N), but user interaction needed (UI:R), and limited impact confined to confidentiality (C:L) without affecting integrity or availability. No known public exploits or patches are currently available, and the vulnerability was published on June 25, 2025. The vulnerability was assigned by the Zero Day Initiative (ZDI) as ZDI-CAN-26732. Given the widespread use of PDF-XChange Editor in business and governmental environments for PDF document handling, this vulnerability represents a potential vector for information leakage and, in combination with other vulnerabilities, could lead to more severe compromises.

For European organizations, the primary risk posed by CVE-2025-6657 is the unauthorized disclosure of sensitive information residing in the memory space of PDF-XChange Editor processes. This could include confidential document content, user credentials, or other sensitive data temporarily loaded during PDF processing. Although the vulnerability alone does not allow code execution, attackers may leverage it as part of a multi-stage attack chain to escalate privileges or execute arbitrary code, thereby compromising endpoint security. Organizations in sectors such as finance, legal, government, and critical infrastructure that rely heavily on PDF-XChange Editor for document management are at heightened risk. The requirement for user interaction means phishing or social engineering campaigns could be used to deliver malicious PDFs. Additionally, the vulnerability could be exploited in targeted attacks against high-value entities, potentially exposing sensitive intellectual property or personal data, which would have regulatory and reputational consequences under GDPR and other European data protection laws.

European organizations should implement the following specific mitigations: 1) Restrict the use of PDF-XChange Editor version 10.5.2.395 by enforcing application whitelisting and ensuring users only open PDFs from trusted sources. 2) Deploy endpoint detection and response (EDR) solutions capable of monitoring anomalous behaviors related to PDF processing and memory access patterns. 3) Educate users on the risks of opening unsolicited or unexpected PDF attachments, especially those containing embedded 3D or PRC content. 4) Employ network-level controls such as sandboxing or detonation chambers to analyze suspicious PDF files before delivery to end users. 5) Monitor vendor communications closely for patches or updates addressing this vulnerability and prioritize timely deployment once available. 6) Consider disabling or limiting PRC file parsing features within PDF-XChange Editor through configuration or group policy if feasible. 7) Implement strict email filtering rules to block or quarantine emails with potentially malicious PDF attachments. These measures go beyond generic advice by focusing on controlling the specific attack vector (malicious PDFs with PRC content) and leveraging layered defenses tailored to the vulnerability's characteristics.