CVE-2026-102860 in SharePoint
Summary
by MITRE • 10/13/2026
Improper access control 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 described constitutes a critical flaw within the Microsoft Office SharePoint environment, specifically categorized as an improper access control issue that facilitates privilege escalation via network vectors. This type of defect typically arises when the application fails to properly enforce restrictions on authenticated users regarding which resources or functions they are authorized to perform. In the context of SharePoint, this often involves misconfigured permissions in web applications, site collections, lists, or specific content types where default settings or administrative oversights leave sensitive endpoints accessible to lower-privileged accounts. The core technical flaw lies in the failure of the server-side logic to validate user roles against requested actions before executing them, allowing an attacker who has already gained a foothold within the network perimeter to interact with internal APIs or web services that should be restricted to administrators or higher-level service accounts.
From a technical perspective, this vulnerability aligns closely with CWE-269, which defines Improper Privilege Control, and often overlaps with CWE-862, Missing Authorization. Attackers exploit these weaknesses by crafting specific HTTP requests that target administrative endpoints or configuration pages without possessing the requisite security tokens or role assignments. By manipulating parameters such as user IDs, group memberships, or session states, an attacker can bypass standard authentication checks embedded in the SharePoint framework. This is particularly dangerous because SharePoint serves as a central hub for document management and collaboration within many enterprise environments, meaning that compromising its access controls provides a high-value target for lateral movement and data exfiltration. The attack vector is remote over the network, which corresponds to ATT&CK technique T1078, Valid Accounts, indicating that the attacker leverages legitimate credentials obtained through phishing or credential theft to execute these unauthorized actions.
The operational impact of this vulnerability is severe, as it effectively neutralizes the security boundary between standard users and system administrators. Once an attacker successfully elevates their privileges, they gain the ability to modify site configurations, inject malicious scripts into web parts, create new administrative user accounts, or access sensitive documents stored across the organization's intranet. This level of control allows for persistent backdoors that are difficult to detect using standard monitoring tools, as the actions appear to originate from legitimate administrator sessions. Furthermore, the ability to alter permissions means an attacker can grant themselves ongoing access even if initial credentials are revoked, leading to long-term compromise of the information system. The integrity and confidentiality of corporate data are directly threatened, potentially resulting in significant financial loss, regulatory penalties under frameworks like GDPR or HIPAA, and reputational damage due to public disclosure of a breach stemming from such fundamental security failures.
Mitigation strategies must focus on both immediate remediation and long-term architectural hardening. Immediately, administrators should apply the latest cumulative updates provided by Microsoft that address known access control flaws in SharePoint versions affected by this issue. It is critical to review and tighten permission settings across all site collections, ensuring that the principle of least privilege is strictly enforced; users should only be granted the minimum permissions necessary for their job functions. Regular audits of user roles and group memberships are essential to identify and remove excessive privileges assigned during initial setup or through subsequent administrative changes. Additionally, implementing multi-factor authentication adds a layer of defense against credential theft, reducing the likelihood that an attacker can obtain valid accounts needed to exploit this vulnerability. Network segmentation should also be employed to isolate SharePoint servers from general user networks where possible, limiting the attack surface available for remote exploitation. Continuous monitoring using security information and event management systems configured to detect anomalous administrative activities will help in early detection of any attempted privilege escalation attempts.