CVE-2026-55051 in SharePoint Server
Summary
by MITRE • 07/14/2026
Server-side request forgery (ssrf) in Microsoft Office SharePoint allows an authorized attacker to disclose information over a network.
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Analysis
by VulDB Data Team • 07/15/2026
Server-side request forgery vulnerabilities in Microsoft Office SharePoint represent a critical security weakness that enables authenticated attackers to manipulate the server's behavior and potentially access sensitive internal resources. This particular flaw exists within the SharePoint platform's handling of network requests, allowing malicious users with valid credentials to craft specially crafted requests that can traverse internal networks and retrieve unauthorized information. The vulnerability stems from insufficient validation of user-supplied input that is subsequently used to construct network requests, creating a pathway for attackers to redirect server-side operations to arbitrary destinations.
The technical implementation of this SSRF weakness occurs when SharePoint processes user-provided URLs or network addresses without adequate sanitization or destination validation mechanisms. Attackers can leverage this by submitting malicious URLs through various SharePoint interfaces such as document libraries, web parts, or API endpoints that accept external resource references. The vulnerability typically manifests when the application fails to properly validate that requested resources originate from trusted domains or when it does not implement proper network access controls to prevent lateral movement within internal infrastructure. This flaw operates at the application layer and can be exploited through HTTP or HTTPS requests that bypass normal network security controls.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potential access to internal systems that would normally be protected by network segmentation. An attacker could use this capability to enumerate internal services, access databases, retrieve configuration files from internal servers, or even attempt to pivot to other systems within the corporate network. The vulnerability is particularly dangerous because SharePoint servers often have elevated privileges and access to sensitive data repositories, making successful exploitation potentially catastrophic for organizations. According to CWE-918, this represents a server-side request forgery vulnerability that allows attackers to perform unauthorized requests from the server, while ATT&CK technique T1071.004 covers application layer protocol forwarding which directly relates to how these attacks are executed.
Mitigation strategies should focus on implementing comprehensive input validation and network access controls within SharePoint environments. Organizations must ensure that all user-supplied URLs are properly validated against a whitelist of approved domains, and that internal network access is restricted through proper firewall rules and network segmentation. The implementation of web application firewalls can help detect and block suspicious patterns in incoming requests, while regular security updates and patches from Microsoft should be applied promptly to address known vulnerabilities. Additionally, administrators should configure SharePoint to limit the ability of users to specify external resources that could be exploited for SSRF attacks, particularly in areas such as document sharing, web part configurations, and API integrations. Network monitoring solutions should also be deployed to detect unusual outbound requests from SharePoint servers that may indicate exploitation attempts.