---
id: "CVE-2026-124174"
page: "https://infrastack.ai/live/CVE-2026-124174"
kind: "vulnerability"
aliases: ["CVE-2026-124174"]
title: "Microsoft Excel: heap buffer overflow lets an attacker run code over network"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "other"
products: [{"name": "Microsoft Office Excel", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "Microsoft 365 Apps for Enterprise", "fixed": ["Current Channel 2610 20527.20196"], "affected": "< builds of the 2026-11-10 update", "ecosystem": "vendor"}, {"name": "Office LTSC 2024", "fixed": ["16.0.17932.21140"], "affected": "< 16.0.17932.21140", "ecosystem": "vendor"}, {"name": "Office LTSC 2021", "fixed": ["16.0.14334.21048"], "affected": "< 16.0.14334.21048", "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"}]
ecosystems: ["vendor"]
tags: ["excel", "macos", "microsoft-office", "other", "user-interaction", "windows"]
not_affected_if: []
published_at: "2026-11-10T19:20:44+00:00"
first_seen_at: "2026-11-10T19:25:13+00:00"
updated_at: "2026-11-10T21:29:06+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124174", "first_seen_at": "2026-11-10T19:25:13+00:00"}, {"source": "analyst", "url": "https://app.opencve.io/cve/CVE-2026-124174", "first_seen_at": "2026-11-10T21:29:06+00:00", "cites": ["https://app.opencve.io/cve/CVE-2026-124174", "https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates"]}]
exploit_sources: []
---

# Microsoft Excel: heap buffer overflow lets an attacker run code over network

Link for people: https://infrastack.ai/live/CVE-2026-124174 (this .md is for agents)

A heap-based buffer overflow in Microsoft Office Excel lets an unauthorized attacker run code over a network. The sources give no further detail on the trigger or the affected versions.

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

## Affected

- vendor:Microsoft Office Excel affected range not listed fixed no fixed version listed
- vendor:Microsoft 365 Apps for Enterprise affected < builds of the 2026-11-10 update fixed Current Channel 2610 20527.20196
- vendor:Office LTSC 2024 affected < 16.0.17932.21140 fixed 16.0.17932.21140
- vendor:Office LTSC 2021 affected < 16.0.14334.21048 fixed 16.0.14334.21048
- 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

## How to check

In any Office app: File > Account > About (Windows) and compare the build with the fixed builds in the fix field; Mac: Word > About and compare with 16.115.26110837. Microsoft's MSRC page was JavaScript-only and could not be read, so check it at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-124174 for the exact product list.

## Fix

Install the November 10, 2026 Office security update. Microsoft's release notes list this CVE under 'Office suite' for builds: Current Channel 2610 (20527.20196); Monthly Enterprise 2610 (20527.20194), 2609 (20430.20264), 2608 (20326.20320); Semi-Annual Enterprise 2610 (20527.20192), 2609 (20430.20262), 2608 (20326.20318); Office 2024/2021 Retail 2610 (20527.20196); Office LTSC 2024 16.0.17932.21140; Office LTSC 2021 16.0.14334.21048. Mac fixed build 16.115.26110837 and Office Online Server 16.0.10417.20236 come from the CVE record as mirrored by OpenCVE, not read on Microsoft's page.

## Timeline

- 2026-11-10T19:25:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124174
- 2026-11-10T21:29:06+00:00 analyst https://app.opencve.io/cve/CVE-2026-124174 — Microsoft's Nov 10 2026 release notes list the CVE (under Office suite) with fixed builds; MSRC page unreadable (JS), affected ranges from OpenCVE mirror of CNA record. No exploitation or PoC found. Only fix verified. Title says 'Excel' but Microsoft lists it under Office suite; CNA title says Excel RCE, left as is.

## Documents

- [describes] OpenCVE: CVE-2026-124174 (mirrors Microsoft CNA record) https://app.opencve.io/cve/CVE-2026-124174
- [fix] Release notes for Microsoft Office security updates (Nov 10, 2026) https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates

## From the sources

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

---

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