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 flaw arises from improper memory management where memory not allocated on the heap is freed, leading to undefined behavior. This vulnerability 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 vulnerability impacts confidentiality, integrity, and availability (all rated high). The vulnerability is significant because use-after-free bugs can lead to arbitrary code execution, enabling attackers to escalate privileges or disrupt services. Although no exploits are currently known in the wild and no patches have been released, the vulnerability's presence in a widely used enterprise collaboration platform like SharePoint poses a substantial risk. The CVSS 3.1 vector indicates that exploitation is feasible but requires user interaction, such as opening a malicious file or triggering a crafted action locally. The absence of patches necessitates immediate mitigation steps to reduce exposure until an official fix is available.

For European organizations, this vulnerability could lead to local code execution on SharePoint servers or client systems running SharePoint components, potentially allowing attackers to escalate privileges or disrupt critical collaboration services. Confidential data stored or processed via SharePoint could be exposed or manipulated, impacting data confidentiality and integrity. Availability of SharePoint services could also be compromised, affecting business continuity. Organizations with distributed teams relying on SharePoint Enterprise Server 2016 are particularly vulnerable if local user environments are not tightly controlled. The impact is heightened in sectors such as finance, government, healthcare, and critical infrastructure, where SharePoint is often used for sensitive document management and collaboration. The lack of known exploits currently provides a window for proactive defense, but the high CVSS score indicates that once exploited, the damage could be severe.

1. Restrict local access to SharePoint Enterprise Server 2016 systems to trusted users only, minimizing the attack surface. 2. Implement strict user privilege management and enforce the principle of least privilege to reduce the impact of potential local exploits. 3. Monitor system logs and user activities for unusual behavior indicative of exploitation attempts, such as unexpected process launches or memory corruption signs. 4. Employ application whitelisting and endpoint protection solutions capable of detecting use-after-free exploitation techniques. 5. Educate users about the risks of interacting with untrusted files or links that could trigger the vulnerability. 6. Prepare for rapid deployment of official patches or updates from Microsoft once released, including testing in controlled environments. 7. Consider isolating or segmenting SharePoint servers from general user workstations to limit lateral movement opportunities. 8. Regularly back up critical SharePoint data to enable recovery in case of compromise affecting availability or integrity.