---
id: "CVE-2026-124170"
page: "https://infrastack.ai/live/CVE-2026-124170"
kind: "vulnerability"
aliases: ["CVE-2026-124170"]
title: "Microsoft Excel: heap buffer overflow lets a remote attacker run code"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "vendor"
products: [{"name": "Office LTSC 2021", "fixed": ["16.0.14334.21048"], "affected": "< 16.0.14334.21048", "ecosystem": "vendor"}, {"name": "Office LTSC 2024", "fixed": ["16.0.17932.21140"], "affected": "< 16.0.17932.21140", "ecosystem": "vendor"}, {"name": "Office for Mac (365, LTSC 2021, LTSC 2024)", "fixed": ["16.115.26110837"], "affected": "< 16.115.26110837", "ecosystem": "vendor"}, {"name": "Office Online Server", "fixed": ["16.0.10417.20236"], "affected": "< 16.0.10417.20236", "ecosystem": "vendor"}, {"name": "Microsoft 365 Apps for Enterprise", "fixed": ["see aka.ms/OfficeSecurityReleases"], "affected": "builds before the Nov 10 2026 release for your channel", "ecosystem": "vendor"}]
ecosystems: []
tags: ["macos", "microsoft-excel", "microsoft-office", "vendor", "windows"]
not_affected_if: ["patched-nov-2026"]
published_at: "2026-11-10T19:20:44+00:00"
first_seen_at: "2026-11-10T19:25:13+00:00"
updated_at: "2026-11-10T21:29:10+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124170", "first_seen_at": "2026-11-10T19:25:13+00:00"}, {"source": "analyst", "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-124170", "first_seen_at": "2026-11-10T21:29:10+00:00", "cites": ["https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-124170", "https://app.opencve.io/cve/CVE-2026-124170"]}]
exploit_sources: []
---

# Microsoft Excel: heap buffer overflow lets a remote attacker run code

Link for people: https://infrastack.ai/live/CVE-2026-124170 (this .md is for agents)

Heap-based buffer overflow (CWE-122) in Microsoft Office Excel, fixed in the November 10, 2026 Patch Tuesday updates. Microsoft's CVSS 3.1 vector is 7.5 (AV:N/AC:H/PR:N/UI:R), so a user has to open a crafted file; exploit code maturity is rated Unproven. Not listed as exploited.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Office LTSC 2021 affected < 16.0.14334.21048 fixed 16.0.14334.21048
- vendor:Office LTSC 2024 affected < 16.0.17932.21140 fixed 16.0.17932.21140
- vendor:Office for Mac (365, LTSC 2021, LTSC 2024) affected < 16.115.26110837 fixed 16.115.26110837
- vendor:Office Online Server affected < 16.0.10417.20236 fixed 16.0.10417.20236
- vendor:Microsoft 365 Apps for Enterprise affected builds before the Nov 10 2026 release for your channel fixed see aka.ms/OfficeSecurityReleases

## How to check

In Excel: File > Account > About Excel and compare the build to the fixed builds below. Microsoft 365 Apps: see the Office security release notes (aka.ms/OfficeSecurityReleases) for the November 10, 2026 build of your channel. Office LTSC 2021 needs 16.0.14334.21048 or later, LTSC 2024 needs 16.0.17932.21140 or later, Office for Mac needs 16.115.26110837 or later.

## Fix

Install the November 2026 Office security updates: LTSC 2021 16.0.14334.21048, LTSC 2024 16.0.17932.21140, Office for Mac / LTSC for Mac 2021 and 2024 16.115.26110837, Office Online Server 16.0.10417.20236, Microsoft 365 Apps per the Office release notes for your channel.

## Timeline

- 2026-11-10T19:25:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124170
- 2026-11-10T21:29:10+00:00 analyst https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-124170 — MSRC page is JS-only and returned no text; versions taken from the Microsoft CNA record as mirrored by OpenCVE (not primary read), so nothing marked verified. No exploitation or PoC found; not in KEV.

## Documents

- [advisory] MSRC: Microsoft Office Excel Remote Code Execution Vulnerability CVE-2026-124170 https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-124170
- [describes] OpenCVE: CVE-2026-124170 (mirror of Microsoft CNA record) https://app.opencve.io/cve/CVE-2026-124170

## From the sources

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

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_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_