CVE-2025-54906 is a use-after-free vulnerability classified under CWE-416 affecting Microsoft SharePoint Enterprise Server 2016, specifically version 16.0.0. The vulnerability arises from improper handling of memory that is freed outside the heap, leading to potential memory corruption. This flaw allows an unauthorized attacker with local access to execute arbitrary code on the affected system. The attack vector requires local access (AV:L), low attack complexity (AC:L), no privileges (PR:N), and user interaction (UI:R). The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). The vulnerability was published on September 9, 2025, with no known exploits in the wild at this time. The lack of a patch link indicates that a fix may not yet be publicly available, increasing the urgency for organizations to monitor updates from Microsoft. Exploitation could lead to full system compromise, data theft, or disruption of SharePoint services. The vulnerability is particularly concerning because SharePoint is widely used in enterprise environments for collaboration and document management, making it a valuable target for attackers. The vulnerability's requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk, especially in environments where local access controls are weak or where social engineering could induce user interaction.

For European organizations, the impact of CVE-2025-54906 is significant due to the widespread use of Microsoft SharePoint Enterprise Server 2016 in corporate, governmental, and critical infrastructure sectors. Successful exploitation could lead to unauthorized code execution, potentially allowing attackers to steal sensitive data, disrupt business operations, or move laterally within networks. Confidentiality breaches could expose intellectual property or personal data protected under GDPR, leading to regulatory penalties and reputational damage. Integrity and availability impacts could disrupt collaboration platforms, affecting productivity and critical workflows. The local access requirement means insider threats or compromised endpoints pose a higher risk. Additionally, the lack of an immediate patch increases exposure time, necessitating interim protective measures. European organizations with remote or hybrid workforces may face challenges in enforcing strict local access controls, increasing the attack surface. The high CVSS score reflects the serious nature of this vulnerability and the need for urgent attention.

1. Restrict local access to systems running SharePoint Enterprise Server 2016 by enforcing strict access controls and limiting administrative privileges. 2. Implement robust endpoint security solutions capable of detecting anomalous behavior indicative of exploitation attempts, such as unusual memory operations or code execution patterns. 3. Educate users about the risks of interacting with untrusted content or executing unknown code locally to reduce the likelihood of user interaction exploitation. 4. Monitor system and application logs for signs of memory corruption or unexpected crashes that could indicate exploitation attempts. 5. Prepare for rapid deployment of official patches or updates from Microsoft once released, including testing in controlled environments to ensure stability. 6. Employ network segmentation to isolate SharePoint servers from less trusted network zones, minimizing lateral movement opportunities. 7. Use application whitelisting and privilege management to limit the execution of unauthorized code. 8. Regularly review and update incident response plans to include scenarios involving local privilege escalation and code execution vulnerabilities. 9. Consider temporary compensating controls such as disabling or limiting features that may be exploited until a patch is available.