CVE-2026-55138

Analyzed Analyzed - Analysis Complete

Untrusted Pointer Dereference in Microsoft Office Excel

Publication date: 2026-07-14

Last updated on: 2026-07-15

Assigner: Microsoft Corporation

Description

Untrusted pointer dereference in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-07-14

Last Modified

2026-07-15

Generated

2026-08-03

AI Q&A

2026-07-15

EPSS Evaluated

2026-08-02

NVD

CVE-2026-55138

EUVD

EUVD-2026-44187

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-822	The product obtains a value from an untrusted source, converts this value to a pointer, and dereferences the resulting pointer.

Attack-Flow Graph

Executive Summary

This vulnerability is an untrusted pointer dereference in Microsoft Office Excel. It allows an unauthorized attacker to access and disclose information stored locally on a system where Excel is installed.

Detection Guidance

This vulnerability involves an untrusted pointer dereference in Microsoft Office Excel that allows local information disclosure. Detection typically requires checking for unusual Excel file behavior or memory access patterns. Use Microsoft's official update tool to verify if the latest security patches are applied. Monitor system logs for suspicious Excel-related activities or crashes.

Impact Analysis

An attacker could exploit this to read sensitive data from your device, such as files opened in Excel or other local information. This could lead to unauthorized access to confidential or personal data.

Compliance Impact

This vulnerability could lead to unauthorized data disclosure, which may violate compliance requirements under GDPR, HIPAA, or other regulations. Organizations must address it to maintain data protection standards.

Mitigation Strategies

Apply the latest security updates from Microsoft for affected Office Excel versions as soon as they become available to patch the untrusted pointer dereference issue.

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