CVE-2026-102861 in SharePoint Server
Summary
by MITRE • 10/13/2026
Missing authorization in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as missing authorization within the Microsoft Office SharePoint environment represents a critical flaw in access control mechanisms, specifically allowing for privilege escalation by authenticated users who possess valid credentials but lack the necessary permissions to perform specific administrative actions. This type of defect typically arises when the application fails to properly verify whether an incoming request is authorized to execute a particular function or access sensitive data structures before processing it. In the context of SharePoint, which serves as a central hub for document management and collaboration within many enterprise networks, such a flaw can have severe implications for organizational security posture. An attacker who has obtained valid user credentials through phishing, credential stuffing, or other means can exploit this gap to perform actions that should be restricted to higher-privileged accounts, effectively bypassing the intended role-based access controls implemented by system administrators.
From a technical perspective, this vulnerability aligns with CWE-269, which classifies Improper Privilege Control as an issue where software executes at an elevated privilege level without requiring proper authorization. The operational impact of such a flaw is significant because it allows lateral movement and persistence within the network infrastructure. Once an attacker elevates their privileges to that of a site collection administrator or higher-level SharePoint role, they gain the ability to modify web parts, upload malicious scripts, alter permissions for other users, and potentially access confidential documents stored across various sites. This capability transforms a low-impact credential compromise into a high-severity incident involving data exfiltration and potential ransomware deployment capabilities against critical business assets hosted on the SharePoint platform.
The exploitation of this vulnerability is consistent with techniques observed in the MITRE ATT&CK framework, particularly under T1078 Valid Accounts for initial access or persistence, followed by T1068 Exploitation for Privilege Escalation if additional vectors are leveraged to gain deeper system control. Attackers often utilize automated tools that scan for misconfigured endpoints and exploit these authorization gaps without triggering immediate alerts, as the requests appear legitimate from an authentication standpoint since they originate from valid user sessions. This stealthiness makes detection challenging using traditional signature-based security information and event management systems unless behavioral analytics are employed to detect anomalous privilege changes or unusual administrative activity patterns originating from standard user accounts.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Organizations should immediately apply the latest cumulative updates provided by Microsoft, which address these specific authorization checks in SharePoint Server versions affected by this flaw. Beyond patching, it is crucial to enforce strict least-privilege principles across all SharePoint sites and user groups. Administrators must review existing role assignments regularly to ensure that users are granted only the minimum permissions necessary for their job functions. Implementing multi-factor authentication adds a layer of defense against credential theft, reducing the likelihood of an attacker obtaining valid login details in the first place. Additionally, deploying advanced threat protection solutions capable of monitoring user behavior and detecting anomalous administrative actions can help identify exploitation attempts in real-time, allowing security teams to respond before significant damage occurs. Regular audits of access logs and permission settings are essential for maintaining a robust defense against privilege escalation attacks targeting enterprise collaboration platforms.