CVE-2025-54901 is a buffer over-read vulnerability classified under CWE-126 found in Microsoft Office Excel 2019, specifically version 19.0.0. This vulnerability allows an unauthorized attacker to read memory beyond the intended buffer boundaries when processing Excel files, potentially disclosing sensitive information stored in adjacent memory areas. The flaw arises from improper bounds checking during Excel file parsing, which can be triggered by a specially crafted Excel document. Exploitation requires local access to the target system and user interaction to open the malicious Excel file, but does not require any privileges or prior authentication. The vulnerability impacts confidentiality by leaking information but does not compromise data integrity or system availability. The CVSS v3.1 base score is 5.5 (medium), reflecting the local attack vector (AV:L), low attack complexity (AC:L), no privileges required (PR:N), and required user interaction (UI:R). The scope remains unchanged (S:U), and the impact is high on confidentiality (C:H) but none on integrity (I:N) or availability (A:N). As of the publication date, no known exploits have been reported in the wild, and no official patches have been released, increasing the importance of proactive mitigation. This vulnerability is particularly relevant for environments where sensitive data is processed in Excel files and where local user access cannot be tightly controlled.

For European organizations, this vulnerability poses a risk of local information disclosure, which could lead to leakage of sensitive business or personal data contained in memory adjacent to the vulnerable buffer. Although the attack requires local access and user interaction, insider threats or compromised endpoints could exploit this flaw to gain unauthorized data exposure. This is especially critical for sectors handling confidential information such as finance, healthcare, government, and critical infrastructure. The inability to affect integrity or availability limits the scope of damage, but confidentiality breaches can still result in regulatory penalties under GDPR and damage to organizational reputation. The lack of current exploits reduces immediate risk but also means organizations must remain vigilant and prepare for potential future exploitation. The medium severity rating suggests that while the threat is not critical, it should not be ignored, particularly in high-security environments.

1. Restrict local access to systems running Microsoft Office 2019, ensuring only trusted users can log in. 2. Educate users to avoid opening Excel files from untrusted or unknown sources, emphasizing the risk of local information disclosure. 3. Implement endpoint security solutions that monitor and alert on suspicious file access or memory reading behaviors. 4. Use application whitelisting and privilege management to limit the ability of unauthorized users to execute or open files in Excel. 5. Regularly audit and monitor local user activity for signs of exploitation attempts. 6. Stay informed about Microsoft’s security advisories and apply patches promptly once released. 7. Consider isolating sensitive Excel processing environments or using virtualized desktops to reduce exposure. 8. Employ data loss prevention (DLP) tools to detect and prevent unauthorized data exfiltration from endpoints. These steps go beyond generic advice by focusing on local access control, user behavior, and monitoring tailored to the specific attack vector and impact of this vulnerability.