CVE-2025-54910 is a heap-based buffer overflow vulnerability identified in Microsoft Office 2019, specifically affecting version 19.0.0. This vulnerability arises from improper handling of memory allocation on the heap, which can lead to overwriting adjacent memory regions. An attacker exploiting this flaw can execute arbitrary code locally without requiring any user interaction or privileges. The CVSS v3.1 base score of 8.4 reflects a high severity rating, indicating significant potential impact on confidentiality, integrity, and availability. The attack vector is local, meaning the attacker must have local access to the system, but no privileges or user interaction are necessary, which lowers the barrier for exploitation once local access is obtained. The vulnerability is classified under CWE-122 (Heap-based Buffer Overflow), a common and dangerous class of memory corruption bugs that can lead to code execution, system crashes, or privilege escalation. No known exploits are currently reported in the wild, and no patches have been linked yet, suggesting this is a recently disclosed vulnerability. Given Microsoft Office's widespread use in enterprise environments, this vulnerability poses a substantial risk if exploited, potentially allowing attackers to compromise systems, steal sensitive data, or disrupt operations.

For European organizations, the impact of CVE-2025-54910 could be significant due to the extensive reliance on Microsoft Office 2019 across public and private sectors. Successful exploitation could lead to unauthorized code execution on critical workstations, enabling attackers to deploy malware, ransomware, or conduct espionage activities. Confidential business data, personal information protected under GDPR, and intellectual property could be exposed or altered. The local attack vector means that insider threats or attackers who gain initial footholds via other means (e.g., phishing, physical access) could leverage this vulnerability to escalate their control. The high impact on confidentiality, integrity, and availability could disrupt business continuity and damage organizational reputation. Furthermore, sectors such as finance, government, healthcare, and critical infrastructure in Europe, which heavily depend on Microsoft Office, could face operational and compliance risks if this vulnerability is exploited.

European organizations should proactively monitor for official patches or security advisories from Microsoft and apply updates promptly once available. Until patches are released, organizations should implement strict access controls to limit local access to systems running Microsoft Office 2019, including enforcing least privilege principles and using endpoint protection solutions capable of detecting anomalous behavior related to memory corruption exploits. Network segmentation and application whitelisting can reduce the risk of lateral movement if exploitation occurs. Regularly auditing and monitoring logs for unusual local activity can help detect exploitation attempts early. Additionally, educating users about the risks of unauthorized local access and maintaining robust physical security controls will reduce the attack surface. Organizations should also consider deploying exploit mitigation technologies such as Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) to make exploitation more difficult.