CVE-2026-70251 in SharePoint Server
Summary
by MITRE • 10/14/2026
Server-side request forgery (ssrf) 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 Server-Side Request Forgery flaw within the Microsoft Office SharePoint environment, presenting a significant risk for privilege escalation and lateral movement across internal networks. This type of attack exploits the server's trust in user-supplied input by forcing it to make HTTP requests to unintended destinations that are typically inaccessible from external networks. In the context of SharePoint, an authorized attacker can manipulate specific parameters or configurations within the application to direct backend processes toward internal services, such as metadata storage endpoints, database interfaces, or other administrative tools running on localhost or private IP ranges. The core technical flaw lies in the insufficient validation and sanitization of URLs provided by users before they are processed by server-side components like web parts, workflows, or integration points with external data sources.
From a security architecture perspective, this vulnerability aligns closely with CWE-918, which defines Server-Side Request Forgery as a weakness where an application retrieves a remote resource without validating the user-supplied URL. By leveraging SSRF, attackers can bypass firewalls and access control lists that restrict direct external access to internal systems. The operational impact is severe because it allows for reconnaissance of the internal network topology, identification of running services on non-standard ports, and potential exploitation of other vulnerabilities in those backend services. For instance, an attacker might probe for exposed management interfaces or exploit weak authentication mechanisms on internal APIs by making requests from the server's own context, which often carries higher privileges than a standard user session.
This attack vector is frequently associated with MITRE ATT&CK technique T1557, specifically Adversary-in-the-Middle, as it can be used to intercept or manipulate communications between services within the network. It also relates to T1046, Network Service Discovery, where the attacker uses the server's outbound connections to map out available resources. The ability to elevate privileges stems from the fact that SharePoint often runs with elevated permissions relative to standard user accounts when interacting with backend databases and system components. Consequently, successful exploitation can lead to unauthorized access to sensitive data stored in SQL Server instances or other database systems connected to the SharePoint farm, potentially resulting in full compromise of the application tier if combined with further exploits targeting those internal services.
Mitigation strategies must focus on strict input validation and network segmentation. Developers should implement allowlists for permitted URLs rather than relying solely on blocklists, ensuring that only explicitly trusted domains or IP ranges are accessible through server-side requests. Additionally, implementing egress filtering at the firewall level to restrict outbound connections from SharePoint servers to known necessary endpoints can significantly reduce the attack surface. It is also critical to disable unnecessary features and integrations within SharePoint that might expose SSRF-prone functionality, such as certain web parts or workflow actions that process external content. Regular security assessments and penetration testing should include specific checks for SSRF vulnerabilities in all components that handle user-controlled URLs, ensuring that any new updates or configurations do not reintroduce these risks.