---
id: "CVE-2026-124187"
page: "https://infrastack.ai/live/CVE-2026-124187"
kind: "vulnerability"
aliases: ["CVE-2026-124187"]
title: "Microsoft Excel: use-after-free lets a remote attacker run code"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "Microsoft Excel (Microsoft 365 Apps for Enterprise)", "fixed": ["2610 20527.20196"], "affected": "< Nov 10 2026 build (Current Channel 2610 20527.20196)", "ecosystem": "vendor"}, {"name": "Microsoft Office LTSC 2024", "fixed": ["16.0.17932.21140"], "affected": "< 16.0.17932.21140", "ecosystem": "vendor"}, {"name": "Microsoft Office LTSC 2021", "fixed": ["16.0.14334.21048"], "affected": "< 16.0.14334.21048", "ecosystem": "vendor"}, {"name": "Microsoft Office for Mac (365, LTSC 2021, LTSC 2024)", "fixed": ["16.115.26110837"], "affected": "< 16.115.26110837", "ecosystem": "vendor"}]
ecosystems: []
tags: ["macos", "microsoft-excel", "microsoft-office", "package", "windows"]
not_affected_if: []
published_at: "2026-11-10T19:20:47+00:00"
first_seen_at: "2026-11-10T19:25:13+00:00"
updated_at: "2026-11-10T21:28:08+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-124187", "first_seen_at": "2026-11-10T19:25:13+00:00"}, {"source": "analyst", "url": "https://app.opencve.io/cve/CVE-2026-124187", "first_seen_at": "2026-11-10T21:28:08+00:00", "cites": ["https://app.opencve.io/cve/CVE-2026-124187", "https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates"]}]
exploit_sources: []
---

# Microsoft Excel: use-after-free lets a remote attacker run code

Link for people: https://infrastack.ai/live/CVE-2026-124187 (this .md is for agents)

A memory-handling flaw in Microsoft Office Excel lets an attacker run code on a machine over a network. The sources report a CVSS score of 8.8 and do not say whether it is exploited in the wild.

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

## Affected

- vendor:Microsoft Excel (Microsoft 365 Apps for Enterprise) affected < Nov 10 2026 build (Current Channel 2610 20527.20196) fixed 2610 20527.20196
- vendor:Microsoft Office LTSC 2024 affected < 16.0.17932.21140 fixed 16.0.17932.21140
- vendor:Microsoft Office LTSC 2021 affected < 16.0.14334.21048 fixed 16.0.14334.21048
- vendor:Microsoft Office for Mac (365, LTSC 2021, LTSC 2024) affected < 16.115.26110837 fixed 16.115.26110837

## How to check

In any Office app: File > Account > About (Excel), and compare the build to the fixed builds above. Versions below those builds are affected. Mac: Excel > About Excel; affected if below 16.115.26110837.

## Fix

Install the November 10, 2026 Office update. Microsoft's release notes list this CVE in that release: Current Channel 2610 build 20527.20196; Monthly Enterprise Channel 2610 build 20527.20194, 2609 build 20430.20264, 2608 build 20326.20320; Office LTSC 2024 build 17932.21140; Office LTSC 2021 build 14334.21048; Office 2019 volume 10417.20236. Mac: build 16.115.26110837 per the CVE record (not confirmed on Microsoft's own page).

## Timeline

- 2026-11-10T19:25:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124187
- 2026-11-10T21:28:08+00:00 analyst https://app.opencve.io/cve/CVE-2026-124187 — Fix located on Microsoft's Office security release notes (Nov 10, 2026); fix_status corrected from none. Affected builds from CNA data via OpenCVE; MSRC page not readable via tools. No exploitation or PoC found; vector E:U. Only fix verified.

## Documents

- [describes] OpenCVE: CVE-2026-124187 (CNA data from Microsoft) https://app.opencve.io/cve/CVE-2026-124187
- [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

Use after free 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_