CVE-2026-102866

Analyzed Analyzed - Analysis Complete

Improper Signature Verification in Microsoft Office SharePoint

Publication date: 2026-10-13

Last updated on: 2026-10-14

Assigner: Microsoft Corporation

Description

Improper verification of cryptographic signature in Microsoft Office SharePoint allows an unauthorized attacker to elevate privileges over a network.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-10-13

Last Modified

2026-10-14

Generated

2026-10-19

AI Q&A

2026-10-14

EPSS Evaluated

2026-10-18

NVD

CVE-2026-102866

EUVD

EUVD-2026-99049

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	sharepoint_server	to 16.0.20326.20190 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-347	The product does not verify, or incorrectly verifies, the cryptographic signature for data.

Attack-Flow Graph

Executive Summary

This vulnerability involves improper verification of cryptographic signatures in Microsoft Office SharePoint. An unauthorized attacker can exploit this to gain elevated privileges over a network without needing user interaction.

Impact Analysis

An attacker could gain unauthorized access to sensitive data, modify system configurations, or perform actions with elevated permissions. This could lead to data breaches, unauthorized modifications, or further network compromise.

Compliance Impact

This vulnerability could lead to unauthorized access or data breaches, violating GDPR's data protection requirements or HIPAA's safeguards for protected health information. Non-compliance may result in legal penalties, fines, or reputational damage.

Mitigation Strategies

Apply the latest security updates from Microsoft for SharePoint Server to address the improper cryptographic signature verification issue. Monitor Microsoft's official security advisories for patches and follow their recommended mitigation steps.

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