CVE-2025-54905 is a high-severity vulnerability classified under CWE-822 (Untrusted Pointer Dereference) affecting Microsoft SharePoint Enterprise Server 2016, specifically version 16.0.0. The vulnerability arises from an untrusted pointer dereference in Microsoft Office Word components used within SharePoint. This flaw allows an unauthorized attacker to cause local information disclosure. The vulnerability requires local access (Attack Vector: Local) and user interaction (UI:R), but no privileges are required (PR:N). The attacker can exploit this vulnerability by tricking a user into opening a malicious Word document within the SharePoint environment, leading to disclosure of sensitive information. The CVSS v3.1 base score is 7.1, indicating a high severity with a high impact on confidentiality (C:H), no impact on integrity (I:N), and a high impact on availability (A:H). The vulnerability does not require elevated privileges but does require user interaction, and the scope remains unchanged (S:U). No known exploits are currently in the wild, and no patches have been linked yet. The vulnerability was reserved in late July 2025 and published in early September 2025, indicating it is a recent discovery. The technical root cause is the dereferencing of pointers that are not properly validated, leading to potential memory corruption or access to unauthorized memory areas, which can be leveraged to disclose sensitive information locally within the SharePoint server environment.

For European organizations, especially those heavily reliant on Microsoft SharePoint Enterprise Server 2016 for document management and collaboration, this vulnerability poses a significant risk. The local information disclosure could lead to leakage of sensitive corporate data, intellectual property, or personal data protected under GDPR. The high impact on availability suggests that exploitation might also cause service disruptions, affecting business continuity. Since the vulnerability requires local access and user interaction, insider threats or compromised endpoints within the corporate network could be leveraged to exploit this flaw. This is particularly concerning for sectors with strict data protection requirements such as finance, healthcare, and government institutions across Europe. The absence of known exploits currently provides a window for mitigation, but the high severity score demands urgent attention to prevent potential targeted attacks or insider misuse.

European organizations should implement the following specific mitigations: 1) Restrict local access to SharePoint servers strictly to trusted administrators and users, minimizing the attack surface. 2) Enforce strict endpoint security policies to prevent execution of untrusted or malicious Word documents, including application whitelisting and advanced threat protection solutions that scan documents for malicious content. 3) Educate users about the risks of opening untrusted documents, especially within SharePoint environments. 4) Monitor SharePoint server logs and endpoint behavior for unusual activities indicative of exploitation attempts. 5) Apply any forthcoming security patches from Microsoft immediately upon release. 6) Consider upgrading to a more recent, supported version of SharePoint if feasible, as older versions may lack security improvements. 7) Implement network segmentation to isolate SharePoint servers from less trusted network zones to reduce the risk of local exploitation. 8) Use Data Loss Prevention (DLP) tools to detect and prevent unauthorized data exfiltration that could result from this vulnerability.