CVE-2026-65807

Analyzed Analyzed - Analysis Complete

Type Confusion in Microsoft Office Excel

Publication date: 2026-08-11

Last updated on: 2026-08-13

Assigner: Microsoft Corporation

Description

Access of resource using incompatible type ('type confusion') in Microsoft Office Excel allows an unauthorized 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

2026-08-11

EPSS Evaluated

2026-08-30

NVD

CVE-2026-65807

EUVD

EUVD-2026-56445

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	microsoft_365	*
microsoft	office_2021	*
microsoft	office_2021	*
microsoft	office_2021	*
microsoft	office_2024	*
microsoft	office_2024	*
microsoft	office_2024	*

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 vulnerability is a type confusion issue in Microsoft Office Excel. It allows an unauthorized attacker to execute arbitrary code remotely by exploiting how Excel handles data types. This occurs when the software accesses a resource using an incompatible type, leading to unexpected behavior.

Detection Guidance

This vulnerability involves type confusion in Microsoft Office Excel leading to remote code execution. Detection primarily relies on monitoring for suspicious Excel file activity or known indicators of compromise. Check for unexpected Excel processes, unusual network connections from Excel, or files with malicious macros. Use endpoint detection tools like Microsoft Defender for Office 365 to scan for exploits targeting this CVE.

Impact Analysis

An attacker could exploit this to run malicious code on your system if you open a specially crafted Excel file. This could lead to data theft, system compromise, or further network attacks. The impact depends on user privileges and system configuration.

Compliance Impact

This vulnerability allows remote code execution via type confusion in Microsoft Office Excel, which could lead to unauthorized data access or modification. Such risks may impact compliance with GDPR (data protection) and HIPAA (health data security) by enabling breaches of sensitive information.

Mitigation Strategies

Apply the latest security updates from Microsoft to patch the vulnerability in Microsoft Office Excel. Monitor Microsoft's security advisories for updates and ensure all systems are updated promptly.

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