CVE-2026-64901 in SharePoint
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 in Microsoft Office SharePoint that enables remote code execution through crafted malicious data payloads. The issue stems from the application's improper handling of untrusted data during the deserialization process, where maliciously constructed objects are automatically converted from serialized format back into executable code. This weakness allows an authenticated attacker with limited privileges to craft specially formatted data that when processed by SharePoint's deserialization mechanism triggers arbitrary code execution on the target system. The vulnerability exists within the server-side processing logic that handles various data formats including but not limited to xml and binary serialized objects, making it particularly dangerous as attackers can leverage multiple vectors to exploit this flaw.
The technical implementation of this vulnerability aligns with common CWE categories such as CWE-502 Deserialization of Untrusted Data and CWE-94 Improper Control of Generation of Code, where the application fails to validate or sanitize input data before processing it through deserialization routines. Attackers can exploit this by uploading malicious files or manipulating existing SharePoint objects that contain serialized payloads designed to execute shell commands or establish reverse shells on the compromised system. The attack surface extends across multiple SharePoint components including document libraries, list items, and web part configurations where user-supplied data is processed without proper sanitization checks.
From an operational impact perspective, this vulnerability enables attackers to escalate privileges from authenticated users to full system compromise, potentially allowing them to access sensitive corporate data, modify existing content, or establish persistent backdoors within the SharePoint environment. The attack can be executed remotely over network connections without requiring local system access, making it particularly dangerous in enterprise environments where SharePoint servers are accessible from multiple network segments. Organizations may experience data breaches, unauthorized modifications to critical business documents, and potential lateral movement throughout their network infrastructure as attackers leverage the compromised SharePoint server as a foothold for further infiltration.
Security mitigations should focus on implementing strict input validation and sanitization procedures for all data that flows into SharePoint's deserialization processes. Organizations should deploy web application firewalls to monitor and filter suspicious serialized data patterns, implement least privilege access controls to limit user permissions, and regularly update SharePoint installations to apply Microsoft security patches. The recommended approach includes disabling unnecessary deserialization features, implementing strict content type restrictions, and establishing monitoring protocols to detect anomalous data processing activities. Additionally, organizations should consider implementing application whitelisting policies that restrict which serialized data formats can be processed within SharePoint environments, aligning with defense-in-depth strategies outlined in the MITRE ATT&CK framework under the execution and privilege escalation categories. Regular security assessments and penetration testing should be conducted to identify and remediate similar vulnerabilities across the entire SharePoint ecosystem.