CVE-2026-70329

Analyzed Analyzed - Analysis Complete

Integer Overflow in Microsoft Office Outlook Allows Code Execution

Publication date: 2026-08-11

Last updated on: 2026-08-14

Assigner: Microsoft Corporation

Description

Integer overflow or wraparound in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-08-11

Last Modified

2026-08-14

Generated

2026-09-01

AI Q&A

2026-08-11

EPSS Evaluated

2026-08-30

NVD

CVE-2026-70329

EUVD

EUVD-2026-56585

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	365_apps	*
microsoft	365_apps	*
microsoft	outlook	2016
microsoft	outlook	2016
microsoft	office_2019	*
microsoft	office_2019	*
microsoft	office_2021	*
microsoft	office_2021	*
microsoft	office_2024	*
microsoft	office_2024	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-190	The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

Attack-Flow Graph

Executive Summary

This vulnerability is an integer overflow or wraparound flaw in Microsoft Office Outlook. It allows an unauthorized attacker to execute arbitrary code remotely over a network without needing prior access.

Detection Guidance

This vulnerability involves an integer overflow in Microsoft Office Outlook allowing remote code execution. Detection requires checking for unusual network activity or suspicious Outlook processes. Use network monitoring tools like Wireshark to inspect traffic for unexpected payloads targeting Outlook. Check system logs for crashes or errors in Outlook.exe. Ensure Outlook is updated to the latest patch from Microsoft.

Impact Analysis

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

Compliance Impact

This vulnerability allows remote code execution via an integer overflow in Microsoft Office Outlook, which could lead to unauthorized access to sensitive data. Such breaches may violate GDPR's data protection requirements and HIPAA's safeguards for protected health information if exploited.

Mitigation Strategies

Apply the latest security updates from Microsoft for Office Outlook as soon as possible to patch the integer overflow vulnerability.

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