CVE-2026-20957
Unknown Unknown - Not Provided
Integer Underflow in Microsoft Excel Enables Local Code Execution

Publication date: 2026-01-13

Last updated on: 2026-01-13

Assigner: Microsoft Corporation

Description
Integer underflow (wrap or wraparound) in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
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Meta Information
Published
2026-01-13
Last Modified
2026-01-13
Generated
2026-06-16
AI Q&A
2026-01-14
EPSS Evaluated
2026-06-15
NVD
CVE-2026-20957
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
microsoft office_excel *
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-191 The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
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().
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Executive Summary

This vulnerability is an integer underflow (wrap or wraparound) in Microsoft Office Excel that allows an unauthorized attacker to execute code locally on the affected system. [1]

Impact Analysis

This vulnerability can allow an unauthorized attacker to execute code locally, potentially leading to full compromise of the affected system including confidentiality, integrity, and availability impacts. [1]

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