CVE-2026-102865 in SharePoint Server
Summary
by MITRE • 10/13/2026
Incorrect authorization in Microsoft Office SharePoint allows an authorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability described constitutes a critical flaw within the authentication and access control mechanisms of Microsoft Office SharePoint, specifically categorized under CWE-285 Improper Authorization. This security defect arises from insufficient validation checks during request processing, allowing individuals who have already authenticated to the system to perform actions or access resources that exceed their assigned privileges. In typical enterprise environments, SharePoint serves as a central repository for sensitive corporate documents, project data, and internal communications. The failure to enforce strict role-based access controls means that an attacker with valid credentials can bypass intended restrictions on specific endpoints or API calls designed to retrieve metadata or content from the server.
From a technical perspective, this flaw likely stems from inconsistent enforcement of authorization policies across different components of the SharePoint architecture. While users may be correctly authenticated via Kerberos or NTLM protocols, the application fails to verify whether the authenticated user possesses the necessary permissions for the specific resource being requested. This discrepancy allows an authorized attacker to craft malicious requests that target internal APIs or web services responsible for serving document libraries and site collections. By manipulating these requests, the attacker can extract confidential information such as proprietary business strategies, financial records, employee personal data, or intellectual property without triggering standard security alerts associated with unauthorized access attempts from external actors.
The operational impact of this vulnerability is severe due to its potential for widespread data exfiltration. Since SharePoint often hosts mission-critical organizational assets, the disclosure of sensitive information can lead to significant competitive disadvantage, regulatory non-compliance under frameworks such as GDPR or HIPAA if personal health or financial data is involved, and reputational damage. Furthermore, because the attacker operates using valid credentials, their activities may blend in with normal user traffic, making detection through traditional perimeter security tools difficult. This aligns with MITRE ATT&CK techniques related to Data from Information Repositories (T1213) and potentially Account Manipulation if the attacker uses compromised accounts to maintain persistence while exfiltrating data.
Mitigation strategies must focus on immediate patching of affected SharePoint versions as provided by Microsoft, alongside rigorous review of access control lists within the organization's deployment. Administrators should implement strict least-privilege principles, ensuring that users are granted only the minimum permissions necessary for their roles. Additionally, deploying Web Application Firewalls with rules specifically tuned to detect anomalous API usage patterns can help identify and block exploitation attempts in real-time. Continuous monitoring of SharePoint logs for unusual data access volumes or requests from unexpected user-agent strings is also recommended to enhance visibility into potential abuse of this authorization flaw.