---
id: CVE-2026-81959
title: >-
  Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized
  attacker to execute code locally.
summary: >-
  Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized
  attacker to execute code locally.
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H'
cwe:
  - CWE-122
  - CWE-190
vendor: microsoft
product: 365_apps
affected:
  - 365_apps
  - excel = 2016
  - microsoft_365
  - office_2016
  - office_2019
  - office_2021
  - office_2024
published: '2026-09-08'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T20:18:42.487'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-81959'
references:
  - url: 'https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-81959'
    label: secure@microsoft.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-09-09T04:19:39.633687Z'
epss: 0.00426
epssPercentile: 0.36361
ingestedAt: '2026-09-08T19:08:49.632Z'
---

## Overview

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

## Affected

- `365_apps`
- `excel = 2016`
- `microsoft_365`
- `office_2016`
- `office_2019`
- `office_2021`
- `office_2024`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.