CVE-2026-55137

Analyzed Analyzed - Analysis Complete

Heap-based Buffer Overflow in Microsoft Office Excel

Publication date: 2026-07-14

Last updated on: 2026-07-15

Assigner: Microsoft Corporation

Description

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

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-07-14

Last Modified

2026-07-15

Generated

2026-08-04

AI Q&A

2026-07-15

EPSS Evaluated

2026-08-02

NVD

CVE-2026-55137

EUVD

EUVD-2026-44202

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	*
microsoft	office_online_server	to 16.0.10417.20175 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-122	A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

Attack-Flow Graph

Executive Summary

This is a heap-based buffer overflow vulnerability in Microsoft Office Excel. It allows an unauthorized attacker to execute arbitrary code on a victim's system by exploiting memory corruption in Excel's processing of certain files.

Detection Guidance

Detecting this vulnerability requires checking for vulnerable versions of Microsoft Excel or Office applications. Use the following commands to identify installed versions: On Windows, run 'wmic product where "name like 'Microsoft Office%%'" get name, version' or 'Get-WmiObject -Class Win32_Product | Where-Object {$_.Name -like '*Microsoft Office*'} | Select-Object Name, Version' in PowerShell.

Impact Analysis

An attacker could exploit this to run malicious code on your computer if you open a specially crafted Excel file. This could lead to data theft, installation of malware, or full system compromise depending on user privileges.

Compliance Impact

This vulnerability allows unauthorized code execution, which could lead to unauthorized access or data exfiltration. Such breaches may violate GDPR's data protection requirements or HIPAA's safeguards for protected health information if exploited.

Mitigation Strategies

Apply the latest security updates from Microsoft for Excel as soon as possible to patch the heap-based buffer overflow vulnerability.

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