CVE-2025-29793 in SharePoint
Summary
by MITRE • 04/08/2025
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 • 07/08/2026
This vulnerability represents a critical deserialization flaw in Microsoft Office SharePoint that enables remote code execution through crafted malicious data streams. The vulnerability stems from the application's improper handling of untrusted input during the deserialization process, where SharePoint fails to adequately validate or sanitize data received from external sources. When an authenticated attacker successfully exploits this weakness, they can inject malicious serialized objects that execute arbitrary code on the target system with the privileges of the SharePoint service account.
The technical implementation of this vulnerability involves the manipulation of serialized data structures that SharePoint processes during normal operations such as web part rendering, list item handling, or user profile management. When the application attempts to deserialize these objects without proper validation mechanisms, it inadvertently executes malicious payloads embedded within the serialized content. This type of vulnerability falls under CWE-502 which specifically addresses deserialization of untrusted data, making it a well-documented and dangerous class of security flaws that has affected numerous enterprise applications.
From an operational perspective, this vulnerability presents significant risk to organizations relying on SharePoint as their primary collaboration platform since successful exploitation can lead to complete system compromise. Attackers can leverage this weakness to establish persistent backdoors, escalate privileges, access sensitive corporate data, or use the compromised server as a launchpad for lateral movement within the network infrastructure. The attack surface is particularly concerning because SharePoint servers often run with elevated privileges and may have access to critical internal resources, making them attractive targets for advanced persistent threats.
The impact extends beyond immediate code execution to encompass broader security implications including data exfiltration, system integrity compromise, and potential disruption of business operations. Organizations may face regulatory compliance violations, financial losses, and reputational damage if such vulnerabilities are exploited successfully. The exploitation typically requires minimal privileges since SharePoint's authentication mechanisms are bypassed through the deserialization attack vector rather than traditional credential theft approaches.
Mitigation strategies should focus on implementing robust input validation, disabling unnecessary deserialization capabilities, and applying Microsoft security patches promptly. Organizations should also consider network segmentation to limit access to SharePoint servers, implement strict firewall rules, and deploy intrusion detection systems to monitor for suspicious deserialization activity. Additionally, following the principle of least privilege and regularly auditing SharePoint configurations can help reduce the potential impact of such vulnerabilities. The ATT&CK framework categorizes this type of attack under T1059.007 for remote code execution through serialized objects, highlighting the need for comprehensive defensive measures across multiple security layers to protect against sophisticated exploitation techniques that target serialization weaknesses in enterprise collaboration platforms.