CVE-2026-66807

Analyzed Analyzed - Analysis Complete

Stack-based Buffer Overflow in Microsoft Office

Publication date: 2026-08-11

Last updated on: 2026-08-14

Assigner: Microsoft Corporation

Description

Stack-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-11

Last Modified

2026-08-14

Generated

2026-09-01

AI Q&A

2026-08-12

EPSS Evaluated

2026-08-30

NVD

CVE-2026-66807

EUVD

EUVD-2026-56749

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	365_apps	*
microsoft	365_apps	*
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-121	A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

Attack-Flow Graph

Executive Summary

This is a stack-based buffer overflow vulnerability in Microsoft Office. It allows an unauthorized attacker to execute arbitrary code on a local system by exploiting a flaw in how Office handles certain data.

Detection Guidance

Detection requires monitoring for unusual activity or crashes in Microsoft Office applications. Check for buffer overflow indicators in logs or memory dumps. Use tools like Process Monitor or Windows Event Viewer to track suspicious Office processes.

Impact Analysis

An attacker could exploit this to run malicious code on your computer, potentially stealing data, installing malware, or taking control of your system. It requires user interaction, such as opening a specially crafted file.

Compliance Impact

The vulnerability allows unauthorized code execution, which could lead to unauthorized access or data breaches. This may impact compliance with GDPR by risking personal data exposure and HIPAA by compromising protected health information if exploited.

Mitigation Strategies

Apply the latest security updates from Microsoft for Office products immediately to patch the stack-based buffer overflow vulnerability.

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