CVE-2025-6643 is a security vulnerability classified as an out-of-bounds read (CWE-125) in the PDF-XChange Editor, specifically affecting version 10.5.2.395. The flaw resides in the parsing of U3D (Universal 3D) files, a format used for embedding 3D content within PDFs. Due to insufficient validation of user-supplied data during U3D file parsing, the application may read memory beyond the allocated bounds. This can lead to information disclosure, allowing an attacker to access sensitive data from the application's memory space. Exploitation requires user interaction, such as opening a malicious PDF file or visiting a malicious webpage containing crafted U3D content. While the vulnerability itself primarily results in information disclosure, it can be chained with other vulnerabilities to achieve arbitrary code execution within the context of the current process. The vulnerability has a CVSS 3.0 base score of 3.3, indicating a low severity level, with an attack vector limited to local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), and user interaction required (UI:R). No known exploits are currently in the wild, and no patches have been published at the time of analysis. The vulnerability was assigned and published by the Zero Day Initiative (ZDI) under identifier ZDI-CAN-26532.

For European organizations, the primary impact of CVE-2025-6643 is the potential disclosure of sensitive information from memory when users open malicious PDF documents containing crafted U3D files. This could lead to leakage of confidential data, such as credentials, personal information, or proprietary business data, depending on what resides in the memory at the time of exploitation. Although the vulnerability alone does not allow code execution, its potential to be combined with other vulnerabilities raises the risk of more severe attacks, including remote code execution and system compromise. Organizations in sectors with high reliance on PDF-XChange Editor for document handling—such as legal, finance, government, and engineering—may face increased risk. The requirement for user interaction limits the attack surface but does not eliminate risk, especially in environments where users frequently handle external or untrusted PDF files. The low CVSS score reflects limited impact and exploitation complexity; however, the strategic importance of protecting sensitive documents in European organizations means even low-severity vulnerabilities warrant attention.

Implement strict email and web filtering to block or flag PDF files containing U3D content from untrusted sources. Educate users on the risks of opening unsolicited or suspicious PDF attachments, emphasizing caution with files containing 3D content. Deploy endpoint detection and response (EDR) solutions capable of monitoring anomalous behavior related to PDF-XChange Editor processes. Restrict the use of PDF-XChange Editor to trusted documents only, and consider disabling or limiting U3D rendering features if not required. Regularly audit and inventory software versions across the organization to identify and prioritize updates once patches become available. Use sandboxing or isolated environments for opening untrusted PDF files to contain potential exploitation attempts. Monitor vendor communications and security advisories for the release of patches or updates addressing this vulnerability and apply them promptly.