CVE-2025-54901 is a medium-severity vulnerability identified in Microsoft Office 2019, specifically affecting the Excel component (version 19.0.0). The vulnerability is classified as a CWE-126: Buffer Over-read, which occurs when a program reads data beyond the boundaries of a buffer. In this case, the flaw allows an unauthorized attacker to cause Microsoft Excel to read memory beyond the intended buffer limits. This can lead to the disclosure of sensitive information stored in adjacent memory regions. The vulnerability requires local access (Attack Vector: Local) and does not require any privileges (Privileges Required: None), but it does require user interaction (User Interaction: Required), such as opening a maliciously crafted Excel file. The scope of the vulnerability is unchanged (Scope: Unchanged), and the impact is limited to confidentiality (Confidentiality: High), with no impact on integrity or availability. The CVSS v3.1 base score is 5.5, reflecting a medium severity level. There are no known exploits in the wild at the time of publication, and no patches have been linked yet. The vulnerability was reserved on July 31, 2025, and published on September 9, 2025. The technical nature of the buffer over-read suggests that an attacker could craft a specially designed Excel spreadsheet that, when opened by a user, causes Excel to read and potentially disclose sensitive information from memory, which could include other documents, credentials, or system data residing in memory. Since the attack requires local access and user interaction, it is less likely to be exploited remotely but could be leveraged in targeted attacks or through social engineering to trick users into opening malicious files.

For European organizations, the impact of CVE-2025-54901 could be significant in environments where Microsoft Office 2019 is widely deployed, especially in sectors handling sensitive or confidential information such as finance, government, healthcare, and legal services. The confidentiality breach could lead to unauthorized disclosure of sensitive data, potentially violating GDPR and other data protection regulations, resulting in legal and financial repercussions. Since the vulnerability requires local access and user interaction, the risk is higher in scenarios where endpoint security is weak or where users are prone to opening untrusted files, such as in phishing campaigns. The lack of impact on integrity and availability limits the threat to data leakage rather than system disruption or data manipulation. However, the potential for information disclosure could aid attackers in further lateral movement or privilege escalation within an organization. European organizations with remote or hybrid workforces may face increased risk if endpoint devices are not adequately secured or monitored.

To mitigate this vulnerability effectively, European organizations should: 1) Implement strict email and file attachment filtering to reduce the risk of malicious Excel files reaching end users. 2) Educate users about the risks of opening unsolicited or suspicious Excel documents, emphasizing cautious behavior with email attachments and downloads. 3) Employ endpoint detection and response (EDR) solutions capable of detecting anomalous behavior related to memory access or suspicious file openings in Microsoft Office. 4) Restrict local user permissions to the minimum necessary to reduce the impact of local exploits. 5) Monitor and control the use of removable media and file sharing to limit the spread of malicious files. 6) Stay alert for official patches or updates from Microsoft and apply them promptly once available. 7) Consider deploying application whitelisting or sandboxing technologies to isolate Office applications and limit the potential damage from malicious files. 8) Conduct regular security awareness training focused on social engineering and phishing tactics that could deliver such malicious files.