CVE-2025-6656 is a security vulnerability identified in PDF-XChange Editor version 10.5.2.395, specifically related to the parsing of PRC files within PDF documents. The vulnerability is classified as an out-of-bounds read (CWE-125), where the software fails to properly validate user-supplied data during PRC file parsing. This flaw allows an attacker to read memory beyond the intended boundaries of an allocated object, potentially disclosing sensitive information from the process memory. Exploitation requires user interaction, such as opening a maliciously crafted PDF file or visiting a malicious webpage that triggers the vulnerable parsing routine. Although the vulnerability itself is an information disclosure issue, it can be leveraged in combination with other vulnerabilities to achieve arbitrary code execution within the context of the current process. The CVSS v3.0 base score is 3.3, indicating a low severity primarily due to the requirement for local access vector (AV:L), no privileges required (PR:N), and user interaction (UI:R). The vulnerability does not impact integrity or availability directly but compromises confidentiality by leaking memory contents. No patches or known exploits in the wild have been reported as of the publication date (June 25, 2025). The vulnerability was assigned by the Zero Day Initiative (ZDI) under the identifier ZDI-CAN-26731.

For European organizations, the primary impact of CVE-2025-6656 is the potential leakage of sensitive information from memory when users open malicious PDF files containing crafted PRC data. This could lead to exposure of confidential data such as credentials, personal information, or internal documents. While the vulnerability alone does not allow code execution, its exploitation in conjunction with other vulnerabilities could escalate to full compromise of affected systems. Organizations in sectors handling sensitive or regulated data—such as finance, healthcare, government, and critical infrastructure—may face increased risk if attackers combine this flaw with other exploits. The requirement for user interaction limits the attack surface to scenarios involving phishing or malicious document distribution. However, given the widespread use of PDF-XChange Editor in Europe, especially in professional and governmental environments, the risk of targeted attacks exploiting this vulnerability exists. The low CVSS score suggests limited immediate threat, but the potential for information disclosure and subsequent exploitation warrants attention.

To mitigate the risk posed by CVE-2025-6656, European organizations should implement the following specific measures: 1) Restrict or monitor the use of PDF-XChange Editor version 10.5.2.395, prioritizing updates to patched versions once available. Since no patch is currently released, consider temporary alternatives or sandboxing PDF-XChange Editor processes to limit data exposure. 2) Employ advanced email and web filtering solutions to detect and block malicious PDF attachments or links that could trigger the vulnerability. 3) Educate users on the risks of opening unsolicited or suspicious PDF files, emphasizing caution with documents from unknown sources. 4) Utilize endpoint detection and response (EDR) tools to monitor for anomalous behaviors indicative of exploitation attempts, especially those involving memory reads or unusual process activity related to PDF-XChange Editor. 5) Implement strict application whitelisting and privilege restrictions to reduce the impact of potential exploitation chaining this vulnerability with others. 6) Conduct regular threat hunting focused on PDF-based attacks and review logs for signs of information disclosure attempts. These targeted actions go beyond generic advice by focusing on controlling the specific attack vectors and limiting the vulnerability's exploitation potential in operational environments.