CVE-2025-49706 is a medium-severity vulnerability classified under CWE-287 (Improper Authentication) affecting Microsoft SharePoint Enterprise Server 2016, specifically version 16.0.0. This vulnerability arises from improper authentication mechanisms within the SharePoint platform, allowing an unauthorized attacker to perform spoofing attacks over a network. Spoofing in this context means that an attacker can masquerade as a legitimate user or system component without proper authentication, potentially bypassing access controls. The vulnerability has a CVSS v3.1 base score of 6.5, indicating a moderate risk level. The vector string (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:F/RL:O/RC:C) reveals that the attack can be executed remotely over the network without any privileges or user interaction, with low attack complexity. The impact affects confidentiality and integrity but not availability. The exploitability is functional but no known exploits are currently observed in the wild. The vulnerability was reserved in June 2025 and published in July 2025, indicating recent discovery and disclosure. The lack of available patches at the time of reporting suggests that organizations must rely on interim mitigations until official updates are released. Given SharePoint's role as a collaborative platform often integrated with sensitive organizational data and workflows, exploitation could lead to unauthorized data disclosure and manipulation, undermining trust and operational security.

For European organizations, this vulnerability poses a significant risk due to the widespread use of Microsoft SharePoint Enterprise Server 2016 in enterprise environments for document management, collaboration, and intranet portals. Unauthorized spoofing could allow attackers to impersonate legitimate users or services, potentially gaining access to confidential documents, internal communications, and business-critical workflows. This could lead to data breaches involving personal data protected under GDPR, resulting in regulatory penalties and reputational damage. Integrity impacts could allow attackers to alter documents or configurations, disrupting business processes or planting malicious content. Although availability is not directly impacted, the indirect consequences of data manipulation or trust erosion could be severe. The remote and unauthenticated nature of the attack vector increases the likelihood of exploitation attempts, especially in environments with exposed SharePoint services or insufficient network segmentation. European organizations with high compliance requirements and sensitive data handling will be particularly vulnerable to the confidentiality and integrity risks posed by this flaw.

1. Immediate network-level controls: Restrict external access to SharePoint Enterprise Server 2016 instances by implementing strict firewall rules and network segmentation to limit exposure to untrusted networks. 2. Use VPN or Zero Trust Network Access (ZTNA) solutions to ensure that only authenticated and authorized users can reach SharePoint services. 3. Monitor network traffic and authentication logs for unusual access patterns or spoofing attempts, employing anomaly detection tools tailored to SharePoint protocols. 4. Apply principle of least privilege on SharePoint user accounts and service accounts to minimize potential damage from compromised identities. 5. Disable or restrict legacy authentication protocols or features within SharePoint that may be susceptible to spoofing. 6. Stay updated with Microsoft security advisories and apply patches immediately once available. 7. Conduct regular security assessments and penetration testing focused on authentication mechanisms within SharePoint environments. 8. Educate IT and security teams about this vulnerability to ensure rapid detection and response to suspicious activities related to authentication spoofing.