CVE-2021-1719 in SharePoint Server
Summary
by MITRE • 01/13/2021
Microsoft SharePoint Elevation of Privilege Vulnerability This CVE ID is unique from CVE-2021-1712.
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Analysis
by VulDB Data Team • 05/04/2025
This vulnerability resides within Microsoft SharePoint Server software and represents a critical elevation of privilege flaw that allows authenticated attackers to gain higher system privileges than initially granted. The vulnerability stems from improper validation of user permissions within the SharePoint authorization framework, specifically affecting how the system handles access control lists and permission boundaries. Attackers who have already established a foothold within the SharePoint environment can exploit this weakness to escalate their privileges and potentially gain administrative access to the entire SharePoint farm or associated systems. The flaw exists in the way SharePoint processes permission requests and validates user credentials during certain administrative operations, creating an avenue for privilege escalation attacks. This vulnerability is particularly concerning because it operates at the authorization level rather than authentication, meaning that even users with limited access can potentially leverage this flaw to gain unauthorized administrative capabilities.
The technical implementation of this vulnerability involves a flaw in SharePoint's permission validation mechanism where the system fails to properly enforce access restrictions during specific server-side operations. When users perform certain administrative actions or access particular resources within SharePoint, the permission checking process does not adequately verify whether the requesting user has sufficient privileges to perform the operation. This creates a scenario where an attacker with basic user permissions can manipulate the system into treating them as having elevated privileges. The vulnerability manifests through improper handling of permission tokens and session management during critical SharePoint operations, allowing attackers to bypass normal security boundaries. According to CWE standards, this corresponds to CWE-284 which describes improper access control vulnerabilities, specifically those related to insufficient authorization checks. The flaw is particularly dangerous because it operates silently within the system, making detection difficult and allowing attackers to maintain persistent elevated access without triggering standard security alerts.
The operational impact of this vulnerability extends beyond simple privilege escalation, potentially enabling attackers to compromise entire SharePoint environments and access sensitive organizational data. Once an attacker successfully exploits this vulnerability, they can access restricted documents, modify SharePoint configurations, create new user accounts, and potentially pivot to other systems within the network infrastructure. The attack surface includes not only the SharePoint server itself but also any integrated systems that rely on SharePoint for authentication or authorization. Organizations with extensive SharePoint deployments face significant risk as this vulnerability can be exploited to gain access to confidential business information, intellectual property, and sensitive communications. The vulnerability's impact is amplified in environments where SharePoint serves as a central hub for collaboration and document management, as attackers can leverage their elevated privileges to manipulate critical business processes and data flows. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and can be used to establish persistent access within the network environment.
Mitigation strategies for this vulnerability require immediate patch management and comprehensive security configuration reviews. Microsoft has released security updates that address this specific flaw, and organizations should prioritize applying these patches to all affected SharePoint servers. Additionally, implementing network segmentation and limiting direct access to SharePoint servers can reduce the attack surface and prevent unauthorized access attempts. Security administrators should conduct thorough permission reviews to ensure that users have the minimum required privileges and that access controls are properly enforced throughout the SharePoint environment. Regular monitoring of SharePoint logs for unusual permission-related activities and unauthorized access attempts should be implemented as part of the security operations center procedures. Organizations should also consider implementing additional security controls such as privileged access management solutions and enhanced logging mechanisms to detect potential exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date security patches and proper access control implementations, as this flaw could be exploited by both external attackers and insider threats with sufficient knowledge of the SharePoint system architecture.