CVE-2026-63514 in SharePoint Server
Summary
by MITRE • 08/11/2026
Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability represents a critical deserialization flaw that exploits the way Microsoft Office SharePoint processes untrusted data inputs, creating a pathway for remote code execution attacks. The vulnerability stems from insufficient validation mechanisms within the SharePoint platform's data handling processes, where user-supplied data is automatically deserialized without proper security checks. When an authenticated attacker submits maliciously crafted serialized data through SharePoint's web services or file upload mechanisms, the system attempts to deserialize this data without adequate sanitization measures. This flaw fundamentally violates secure coding principles and creates a dangerous attack surface that can be leveraged for arbitrary code execution across networked environments.
The technical implementation of this vulnerability involves the exploitation of .NET serialization mechanisms within SharePoint's architecture, where objects are reconstructed from serialized byte streams. Attackers can craft specific payload data that when processed by SharePoint's deserialization engine triggers unintended behavior, allowing malicious code to execute with the privileges of the SharePoint application pool account. This creates a persistent threat vector that can be exploited through various attack vectors including file uploads, web service calls, or even crafted HTTP requests that traverse SharePoint's API endpoints. The vulnerability is particularly dangerous because it requires minimal privileges for exploitation and can be executed remotely without requiring direct system access.
The operational impact of this vulnerability extends far beyond simple code execution, as successful exploitation can lead to complete compromise of the SharePoint environment and underlying infrastructure. Attackers can leverage this weakness to establish persistent backdoors, escalate privileges within the domain, or use the compromised SharePoint server as a launch point for broader network infiltration attacks. The attack surface is significantly expanded due to SharePoint's role in enterprise environments where it often serves as a central collaboration platform with access to sensitive business data and integration points with other systems. This vulnerability can result in data breaches, service disruption, and compliance violations that may trigger regulatory penalties under standards such as gdpr, hipaa, or soc 2 requirements.
Organizations should implement comprehensive mitigation strategies including immediate patching of affected SharePoint versions, network segmentation to isolate SharePoint environments, and enhanced monitoring of deserialization activities within SharePoint logs. Security controls should focus on implementing proper input validation, disabling unnecessary serialization features, and establishing strict access controls for SharePoint services. The vulnerability aligns with CWE-502 which specifically addresses deserialization of untrusted data, and can be mapped to ATT&CK techniques such as T1059 for command execution and T1133 for external remote services. Additional protective measures include deploying web application firewalls, implementing application control policies, and conducting regular security assessments to identify and remediate similar vulnerabilities in other enterprise applications that may utilize similar serialization patterns.