CVE-2026-58644 in SharePoint Server
Summary
by MITRE • 07/14/2026
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability represents a critical deserialization flaw that exists within Microsoft Office SharePoint platforms, creating a pathway for remote code execution through improperly validated user input. The core technical issue stems from the application's failure to adequately sanitize and validate data during the deserialization process, allowing attackers to inject malicious payloads that can be executed in the context of the SharePoint server. This weakness directly maps to CWE-502 which specifically addresses deserialization of untrusted data as a primary attack vector for code execution vulnerabilities. The vulnerability operates by leveraging the normal deserialization mechanisms within SharePoint to transform attacker-controlled data into executable code, bypassing typical security controls and access restrictions that would normally prevent such unauthorized operations.
The operational impact of this vulnerability extends far beyond simple data compromise, as successful exploitation can result in complete system takeover and persistent backdoor access. Attackers can leverage this weakness to establish remote command execution capabilities, potentially gaining administrative privileges within the SharePoint environment and accessing sensitive organizational data. The network-based nature of the attack means that exploitation can occur from external threat actors without requiring local system access or credentials, making it particularly dangerous for organizations with exposed SharePoint instances. This vulnerability directly aligns with ATT&CK technique T1059 which describes remote code execution through various vectors including deserialization attacks targeting enterprise applications.
Organizations utilizing SharePoint platforms face significant risk when this vulnerability remains unpatched, as the attack surface includes all components that process user-supplied data through deserialization mechanisms. The exploitability of this issue is heightened by the fact that SharePoint commonly processes various types of data from external sources including file uploads, web service calls, and user input forms, all of which could potentially serve as entry points for malicious payload injection. Security teams must implement comprehensive monitoring for unusual deserialization activity and network traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates how modern enterprise applications can contain complex serialization mechanisms that create inherent security risks when not properly secured against malicious input validation.
Mitigation strategies should focus on immediate patch deployment from Microsoft as well as implementing multiple layers of defense-in-depth controls. Organizations should restrict SharePoint server access through network segmentation and implement strict input validation for all user-supplied data, particularly focusing on serialized objects that traverse network boundaries. Network monitoring solutions should be configured to detect anomalous deserialization patterns and suspicious outbound connections that may indicate exploitation attempts. Additionally, implementing application whitelisting policies can prevent the execution of unauthorized code even if deserialization attacks succeed. Regular security assessments and penetration testing focused on serialization vulnerabilities should be conducted to identify potential attack vectors within SharePoint environments. The remediation process must also include comprehensive testing of patches in controlled environments before deployment to ensure operational stability while addressing the critical security risk presented by this vulnerability.