CVE-2025-6653 is a vulnerability identified in PDF-XChange Editor version 10.5.2.395, specifically within the PRC file parsing component. The flaw is classified as an out-of-bounds read (CWE-125), where the software fails to properly validate user-supplied data when processing PRC files embedded in PDFs. This improper validation leads to reading beyond the allocated buffer boundaries, which can result in the disclosure of sensitive information from the memory space of the application. 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 primarily leads to information disclosure, it can be chained with other vulnerabilities to achieve arbitrary code execution within the context of the current process. The CVSS 3.0 base score is 3.3, indicating a low severity, with an attack vector of local (AV:L), low attack complexity (AC:L), no privileges required (PR:N), user interaction required (UI:R), unchanged scope (S:U), and impact limited to confidentiality (C:L), with no impact on integrity or availability. No known exploits are currently reported in the wild, and no patches have been published at the time of this report. The vulnerability was assigned by the Zero Day Initiative (ZDI) under the identifier ZDI-CAN-26726 and publicly disclosed on June 25, 2025.

For European organizations, the primary impact of CVE-2025-6653 lies in the potential leakage of sensitive information from the memory of systems running the vulnerable PDF-XChange Editor version 10.5.2.395. Since PDF-XChange Editor is widely used for PDF viewing and editing, especially in sectors like finance, legal, and government, unauthorized disclosure of information could lead to exposure of confidential documents or internal data. Although the vulnerability does not directly allow code execution, the possibility of chaining it with other vulnerabilities raises the risk of more severe compromise. The requirement for user interaction (opening a malicious file) limits the attack surface but does not eliminate risk, especially in environments where users frequently handle external PDFs. The low CVSS score reflects limited impact and exploitation complexity; however, organizations with high confidentiality requirements should consider the risk carefully. The absence of known exploits reduces immediate threat but vigilance is warranted as attackers may develop exploits over time. Disruption to business operations is unlikely, but data confidentiality breaches could have regulatory and reputational consequences under European data protection laws such as GDPR.

1. Immediate mitigation should focus on user awareness and training to avoid opening PDFs from untrusted or unknown sources, especially those containing embedded PRC files. 2. Implement strict email filtering and attachment scanning to detect and quarantine suspicious PDF files before reaching end users. 3. Employ endpoint security solutions capable of detecting anomalous behavior related to PDF processing or memory access violations. 4. Restrict the use of PDF-XChange Editor version 10.5.2.395 by upgrading to the latest version once a patch is released or consider alternative PDF viewers with a better security track record until the vulnerability is addressed. 5. Use application whitelisting and sandboxing techniques to limit the impact of potential exploitation by isolating PDF-XChange Editor processes. 6. Monitor logs and network traffic for unusual activity that may indicate attempts to exploit this or related vulnerabilities. 7. Coordinate with IT and security teams to establish rapid response procedures for any suspected exploitation attempts. These steps go beyond generic advice by focusing on controlling the specific attack vector (malicious PDFs with PRC files) and leveraging layered defenses tailored to the vulnerability's characteristics.