CVE-2025-64667 is a vulnerability classified under CWE-451 (User Interface Misrepresentation) affecting Microsoft Exchange Server Subscription Edition RTM, specifically version 15.02.0.0. The issue arises from the server's user interface incorrectly representing critical information, which can be exploited by an unauthorized attacker over a network to perform spoofing attacks. Spoofing in this context means that an attacker can deceive users or administrators by presenting falsified or misleading UI elements, potentially causing them to make incorrect decisions or trust malicious content. The vulnerability does not directly compromise confidentiality or availability but impacts data integrity by misleading users. The CVSS 3.1 base score is 5.3 (medium), with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction needed (UI:N). The scope remains unchanged (S:U), and the impact is limited to integrity (I:L) without affecting confidentiality or availability. The exploitability is rated as unproven (E:U), with an official fix (RL:O) and confirmed report (RC:C). No patches are currently linked, and no known exploits are reported in the wild. This vulnerability highlights the risk of UI-based deception in critical enterprise software, which can undermine trust and operational security in email systems. Organizations using this Exchange Server version should monitor for updates and be aware of potential spoofing attempts that leverage UI misrepresentation.

For European organizations, the primary impact of CVE-2025-64667 is the risk of spoofing attacks that can mislead users or administrators into trusting falsified information presented via the Exchange Server UI. This can lead to improper administrative actions, misconfiguration, or acceptance of malicious content, potentially disrupting email workflows or internal communications. While confidentiality and availability are not directly affected, the integrity of information and trust in the system can be compromised. Given the widespread use of Microsoft Exchange Server in European enterprises, especially in sectors like finance, government, and critical infrastructure, such spoofing could facilitate further social engineering or targeted attacks. The medium severity indicates a moderate risk, but the lack of required privileges and user interaction increases the likelihood of exploitation attempts. Organizations may face operational disruptions or reputational damage if spoofing leads to erroneous decisions or data manipulation.

1. Monitor Microsoft’s official security advisories closely and apply patches promptly once available for Exchange Server Subscription Edition RTM version 15.02.0.0. 2. Implement enhanced logging and monitoring to detect unusual UI behavior or anomalies in Exchange Server interfaces that could indicate spoofing attempts. 3. Educate administrators and users to verify critical UI information carefully, especially when performing sensitive operations, and to report suspicious UI inconsistencies. 4. Employ network-level protections such as segmentation and intrusion detection systems to limit exposure of Exchange Server interfaces to untrusted networks. 5. Use multi-factor authentication and strict access controls to reduce the risk of unauthorized access that could facilitate exploitation. 6. Consider deploying endpoint protection solutions capable of detecting UI manipulation or spoofing techniques. 7. Conduct regular security awareness training focusing on recognizing spoofing and social engineering attacks related to UI misrepresentation.