CVE-2025-6645 is a high-severity use-after-free vulnerability (CWE-416) found in PDF-XChange Editor version 10.5.2.395, specifically in the parsing of U3D (Universal 3D) files embedded within PDFs. The vulnerability arises because the software fails to verify the existence of an object before performing operations on it, leading to a use-after-free condition. This flaw can be exploited by a remote attacker to execute arbitrary code within the context of the current process. Exploitation requires user interaction, such as opening a maliciously crafted PDF file or visiting a malicious webpage that triggers the vulnerability. The vulnerability has a CVSS 3.0 base score of 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. Although no known exploits are currently observed in the wild, the vulnerability poses a significant risk due to the widespread use of PDF-XChange Editor in various professional and enterprise environments. Successful exploitation could allow attackers to execute arbitrary code, potentially leading to full system compromise, data theft, or disruption of services. The vulnerability was identified and assigned by the Zero Day Initiative (ZDI) as ZDI-CAN-26642 and publicly disclosed on June 25, 2025. No patches or updates have been linked yet, indicating that affected users should exercise caution and apply mitigations promptly once available.

For European organizations, the impact of CVE-2025-6645 is considerable due to the common use of PDF-XChange Editor in sectors such as finance, legal, government, and healthcare, where PDF documents are frequently exchanged and processed. Exploitation could lead to unauthorized code execution, enabling attackers to steal sensitive information, deploy ransomware, or establish persistent footholds within networks. Given the vulnerability affects confidentiality, integrity, and availability, organizations face risks including data breaches, operational disruption, and reputational damage. The requirement for user interaction means phishing or social engineering campaigns could be leveraged to deliver malicious PDFs, increasing the attack surface. Additionally, the lack of a patch at the time of disclosure could prolong exposure, especially in environments with slow update cycles or limited endpoint protection. The vulnerability's exploitation could also impact critical infrastructure entities that rely on PDF workflows, potentially affecting national security or public services in Europe.

1. Immediate mitigation should include disabling or restricting the use of PDF-XChange Editor for opening untrusted or unsolicited PDF files, especially those containing embedded 3D content. 2. Implement strict email filtering and attachment scanning to detect and block malicious PDFs exploiting this vulnerability. 3. Employ endpoint detection and response (EDR) solutions capable of monitoring unusual process behavior indicative of exploitation attempts. 4. Educate users on the risks of opening PDFs from unknown or unexpected sources, emphasizing caution with files containing 3D or multimedia content. 5. Use application whitelisting to limit execution of unauthorized software and scripts that could be used in exploitation chains. 6. Monitor vendor communications closely for patches or updates addressing this vulnerability and prioritize rapid deployment once available. 7. Consider sandboxing PDF viewers or using virtualized environments for opening high-risk documents to contain potential exploits. 8. Review and harden network segmentation to limit lateral movement if exploitation occurs. These targeted mitigations go beyond generic advice by focusing on the specific attack vector (U3D file parsing) and the operational context of PDF-XChange Editor usage.