CVE-2025-29978 is a high-severity use-after-free vulnerability (CWE-416) found in Microsoft 365 Apps for Enterprise, specifically within Microsoft Office PowerPoint version 16.0.1. This vulnerability arises when the application improperly manages memory, allowing an attacker to exploit a dangling pointer that references freed memory. An unauthorized attacker can leverage this flaw to execute arbitrary code locally on the affected system. The vulnerability requires user interaction, such as opening a malicious PowerPoint file, and does not require any prior authentication. The CVSS 3.1 base score of 7.8 reflects a high impact on confidentiality, integrity, and availability, with low attack complexity and no privileges required. Exploitation could lead to full system compromise, including data theft, installation of malware, or disruption of services. Although no known exploits are currently in the wild, the vulnerability's nature and Microsoft Office's widespread use make it a significant risk. The lack of an available patch at the time of publication increases the urgency for mitigation and monitoring.

For European organizations, this vulnerability poses a substantial risk due to the extensive use of Microsoft 365 Apps for Enterprise across various sectors including government, finance, healthcare, and critical infrastructure. Successful exploitation could lead to unauthorized access to sensitive data, intellectual property theft, disruption of business operations, and potential regulatory non-compliance under GDPR due to data breaches. The local code execution capability means attackers could deploy ransomware or other persistent threats, severely impacting operational continuity. Given the reliance on PowerPoint for presentations and document sharing, especially in collaborative environments, the attack vector is highly feasible. The requirement for user interaction means phishing campaigns or malicious document distribution could be effective attack methods, which are common tactics in targeted attacks against European entities.

European organizations should implement a multi-layered mitigation strategy beyond generic advice: 1) Immediately restrict the use of PowerPoint files from untrusted sources and educate users on the risks of opening unsolicited attachments. 2) Employ advanced email filtering and sandboxing solutions to detect and block malicious documents before reaching end users. 3) Utilize application control policies (e.g., Microsoft Defender Application Control) to limit execution of unauthorized code. 4) Monitor endpoint behavior for signs of exploitation attempts, such as unusual memory access patterns or process anomalies. 5) Prepare for rapid deployment of patches once Microsoft releases an official fix by maintaining an up-to-date asset inventory and patch management process. 6) Consider deploying exploit mitigation technologies like Control Flow Guard (CFG) and Data Execution Prevention (DEP) where applicable. 7) Conduct targeted phishing awareness campaigns emphasizing the risks of malicious Office documents. These steps, combined with continuous threat intelligence monitoring, will reduce the attack surface and improve detection capabilities.