CVE-2026-70259 in SharePoint Server
Summary
by MITRE • 10/14/2026
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 • 10/14/2026
The vulnerability identified as Server-Side Request Forgery, or SSRF, within Microsoft Office SharePoint represents a critical class of web application security flaws where the server is induced to make requests on behalf of an untrusted user. In this specific context, the flaw allows an authorized attacker to manipulate the destination address that the SharePoint service uses when making outbound network connections. By exploiting this misconfiguration or logic error, the attacker can force the vulnerable server to send HTTP or other protocol-based requests to internal resources that are typically inaccessible from external networks. This mechanism effectively bypasses perimeter firewalls and access control lists because the traffic originates from a trusted source—the SharePoint application itself—thereby granting the attacker indirect access to sensitive internal infrastructure components such as database servers, management interfaces, cloud metadata endpoints, or other microservices residing within the corporate network segment.
The technical root cause of this SSRF vulnerability lies in how the SharePoint application processes user-supplied input that is subsequently used to construct outbound requests without adequate validation or sanitization. When a legitimate user interacts with certain features of Office SharePoint, such as importing data from external sources, integrating with third-party services, or utilizing specific web parts and add-ins, the system may accept URLs or hostnames provided by the user. If these inputs are not strictly validated against an allow-list of permitted domains or if they fail to properly block requests targeting private IP address ranges (such as 10.x.x.x, 172.16-31.x.x, and 192.168.x.x) or local loopback addresses (127.0.0.1), the application will proceed with the request. An attacker can craft a malicious payload containing URLs that point to internal services, potentially including cloud provider metadata endpoints like those found in AWS, Azure, or GCP, which often contain sensitive authentication credentials and configuration details for running instances.
The operational impact of this vulnerability is severe due to its potential to serve as an initial foothold for deeper network compromise. By disclosing information over the network, the attacker can gather intelligence about the internal architecture, identify live hosts, detect open ports, and potentially extract sensitive data such as session tokens, API keys, or database connection strings from unprotected internal services. In cloud environments, accessing metadata endpoints is particularly dangerous as it may lead to full account takeover if instance credentials are retrieved. Furthermore, this vulnerability can be chained with other flaws to achieve remote code execution or privilege escalation within the SharePoint farm. The ability to pivot through trusted connections allows attackers to move laterally across the network, bypassing traditional security controls that rely on source IP reputation and external access restrictions.
From a classification perspective, this flaw aligns closely with CWE-918, which defines Server-Side Request Forgery (SSRF) flaws where a web application fetches a remote resource without validating the user-supplied URL. It also maps to MITRE ATT&CK technique T1557, specifically Adversary-in-the-Middle or Lateral Tool Transfer variants that leverage SSRF for network reconnaissance and credential theft. The exploitation of this vulnerability typically falls under the Initial Access and Discovery tactics within the ATT&CK framework, as it enables attackers to probe internal networks and gather information necessary for subsequent stages of an attack campaign.
Mitigation strategies must focus on strict input validation and secure configuration practices. Administrators should implement a robust allow-listing mechanism that restricts outbound requests from SharePoint services to only those domains and IP ranges strictly required for business operations. All user-supplied URLs must be validated against this list, ensuring that private IP addresses, link-local addresses, and cloud metadata endpoints are explicitly blocked at the application level rather than relying solely on network-level controls. Additionally, deploying a reverse proxy or web application firewall with SSRF detection capabilities can provide an additional layer of defense by inspecting outbound traffic for suspicious patterns. Regular security assessments and penetration testing should be conducted to identify similar logic flaws in other integrated services within the SharePoint ecosystem, ensuring that no unintended pathways exist for internal network access via server-side requests.