CVE-2025-54910 is a heap-based buffer overflow vulnerability identified in Microsoft Office 2019 version 19.0.0. This vulnerability arises from improper handling of memory allocation on the heap, allowing an attacker to overwrite memory buffers beyond their intended boundaries. Exploitation of this flaw enables an unauthorized attacker to execute arbitrary code locally on the affected system without requiring any privileges or user interaction, as indicated by the CVSS vector (AV:L/AC:L/PR:N/UI:N). The vulnerability impacts confidentiality, integrity, and availability, potentially allowing attackers to gain control over the system, access sensitive data, or disrupt operations. The vulnerability was reserved on July 31, 2025, and published on September 9, 2025, with no patches currently available and no known exploits in the wild. The CWE-122 classification confirms the nature of the vulnerability as a heap-based buffer overflow, a common and dangerous memory corruption issue. The high CVSS score of 8.4 reflects the critical impact and relatively low complexity of exploitation. Microsoft Office 2019 is widely used across enterprises, making this vulnerability a significant concern for organizations relying on this software suite. Attackers with local access could leverage this flaw to escalate privileges or execute malicious payloads, emphasizing the need for immediate mitigation once patches are released.

For European organizations, the impact of CVE-2025-54910 is substantial. Microsoft Office 2019 is extensively deployed across government, financial, healthcare, and industrial sectors in Europe, making the vulnerability a potential vector for local privilege escalation and code execution attacks. Successful exploitation could lead to unauthorized access to sensitive documents, disruption of business processes, and potential lateral movement within networks. Confidentiality breaches could expose personal data protected under GDPR, leading to regulatory penalties and reputational damage. Integrity and availability impacts could disrupt critical operations, especially in sectors like finance and healthcare where Microsoft Office is integral to daily workflows. The lack of required user interaction or privileges lowers the barrier for attackers who have local access, such as through compromised credentials or insider threats. Although no exploits are currently known, the vulnerability's characteristics suggest it could be weaponized rapidly once a proof-of-concept is developed. European organizations must prioritize this vulnerability due to the high potential for damage and the widespread use of the affected product.

1. Monitor Microsoft’s official channels closely for the release of security patches addressing CVE-2025-54910 and apply them immediately upon availability. 2. Until patches are available, restrict local access to systems running Microsoft Office 2019 to trusted personnel only, minimizing the risk of local exploitation. 3. Employ application whitelisting and endpoint protection solutions capable of detecting anomalous behavior indicative of exploitation attempts. 4. Enable and enforce Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) on affected systems to hinder exploitation of memory corruption vulnerabilities. 5. Conduct regular audits of user privileges and remove unnecessary local administrative rights to limit the impact of potential exploitation. 6. Implement network segmentation to contain any compromise resulting from local code execution. 7. Educate employees about the risks of local threats and encourage reporting of suspicious activity. 8. Use advanced threat detection tools that can identify heap overflow exploitation techniques. 9. Prepare incident response plans specifically addressing local privilege escalation and code execution scenarios. 10. Consider upgrading to newer versions of Microsoft Office if they are not affected by this vulnerability or have patches available.