Type Confusion in Microsoft Office Excel

Publication date: 2026-09-08

Last updated on: 2026-09-09

Assigner: Microsoft Corporation

Description

Access of resource using incompatible type ('type confusion') in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-08

Last Modified

2026-09-09

Generated

2026-09-29

AI Q&A

2026-09-09

EPSS Evaluated

2026-09-27

NVD

CVE-2026-81401

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	365_apps	*
microsoft	365_apps	*
microsoft	excel	2016
microsoft	excel	2016
microsoft	office_2019	*
microsoft	office_2019	*
microsoft	office_2016	*
microsoft	office_2016	*
microsoft	microsoft_365	*
microsoft	office_2021	*
microsoft	office_2021	*
microsoft	office_2021	*
microsoft	office_2024	*
microsoft	office_2024	*
microsoft	office_2024	*
microsoft	office_online_server	to 16.0.10417.20207 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-843	The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

Attack-Flow Graph

Executive Summary

This is a type confusion vulnerability in Microsoft Office Excel. It occurs when the software incorrectly handles data types, allowing an attacker to access resources they shouldn't. This can lead to unauthorized information disclosure on the local system.

Impact Analysis

An unauthorized attacker could exploit this to access sensitive information stored on your local machine through Excel files. This includes documents, spreadsheets, or other data processed by vulnerable Excel versions.

Mitigation Strategies

Apply the latest security updates from Microsoft for affected Office Excel versions to patch the type confusion vulnerability.

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