CVE-2026-66805

Undergoing Analysis Undergoing Analysis - In Progress

Deserialization Flaw in Microsoft Office SharePoint Permits Remote Code Execution

Publication date: 2026-08-11

Last updated on: 2026-08-13

Assigner: Microsoft Corporation

Description

Deserialization of untrusted data in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-11

Last Modified

2026-08-13

Generated

2026-09-01

AI Q&A

2026-08-12

EPSS Evaluated

2026-08-30

NVD

CVE-2026-66805

EUVD

EUVD-2026-56747

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	sharepoint_server	2019
microsoft	sharepoint_server	2016
microsoft	sharepoint_server	to 16.0.19725.20522 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-502	The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

Attack-Flow Graph

Executive Summary

This vulnerability involves deserialization of untrusted data in Microsoft Office SharePoint. An authorized attacker can exploit this to execute arbitrary code remotely over a network.

Impact Analysis

An attacker could gain control of SharePoint servers, steal sensitive data, install malware, or disrupt services. This could lead to unauthorized access to confidential information or system downtime.

Compliance Impact

This vulnerability could lead to data breaches, violating GDPR and HIPAA requirements for data protection and confidentiality. Organizations may face fines or legal penalties for non-compliance.

Mitigation Strategies

Apply the latest security updates from Microsoft for SharePoint as soon as possible to patch the deserialization flaw. Monitor Microsoft's advisory for official patches and follow their recommended mitigation steps.

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