---
id: "CVE-2026-124176"
page: "https://infrastack.ai/live/CVE-2026-124176"
kind: "vulnerability"
aliases: ["CVE-2026-124176"]
title: "Microsoft Excel: heap buffer overflow lets a remote attacker run code"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "other"
products: [{"name": "Office LTSC 2024", "fixed": ["16.0.17932.21140"], "affected": ">= 16.0.0, < 16.0.17932.21140", "ecosystem": "vendor"}, {"name": "Office LTSC 2021", "fixed": ["16.0.14334.21048"], "affected": ">= 16.0.1, < 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": "Microsoft 365 Apps for Enterprise", "fixed": [], "affected": "affected, fixed build not given in source read", "ecosystem": "vendor"}]
ecosystems: []
tags: ["excel", "macos", "microsoft-office", "other", "user-interaction", "windows"]
not_affected_if: []
published_at: "2026-11-10T19:20:45+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-2026-124176", "first_seen_at": "2026-11-10T19:25:13+00:00"}, {"source": "analyst", "url": "https://radar.offseq.com/threat/cve-2026-124176-cwe-122-heap-based-buffer-overflow-in-microsoft-microsoft-365-apps-for-enterprise-103cee1e9408cb0c", "first_seen_at": "2026-11-10T21:29:06+00:00", "cites": ["https://radar.offseq.com/threat/cve-2026-124176-cwe-122-heap-based-buffer-overflow-in-microsoft-microsoft-365-apps-for-enterprise-103cee1e9408cb0c"]}]
exploit_sources: []
---

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

Link for people: https://infrastack.ai/live/CVE-2026-124176 (this .md is for agents)

A heap-based buffer overflow in Microsoft Excel lets an unauthorized attacker trigger memory corruption over a network. The sources say an attacker could execute code on the affected machine.

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

## Affected

- vendor:Office LTSC 2024 affected >= 16.0.0, < 16.0.17932.21140 fixed 16.0.17932.21140
- vendor:Office LTSC 2021 affected >= 16.0.1, < 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:Microsoft 365 Apps for Enterprise affected affected, fixed build not given in source read fixed no fixed version listed

## How to check

In Excel open File > Account > About Excel and compare the build with the fixed versions: Windows LTSC 2024 16.0.17932.21140, LTSC 2021 16.0.14334.21048; Mac 16.115.26110837. Anything lower is affected. Microsoft 365 Apps (Windows): update from Account > Update Options and confirm against Microsoft's Nov 2026 security update notes.

## Fix

Update Office to: Office LTSC 2024 16.0.17932.21140; Office LTSC 2021 16.0.14334.21048; Office for Mac (365, LTSC 2021, LTSC 2024) 16.115.26110837. 365 Apps for Enterprise (Windows) build not listed in the source read; take the current-channel update from Microsoft's release notes.

## Timeline

- 2026-11-10T19:25:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-124176
- 2026-11-10T21:29:06+00:00 analyst https://radar.offseq.com/threat/cve-2026-124176-cwe-122-heap-based-buffer-overflow-in-microsoft-microsoft-365-apps-for-enterprise-103cee1e9408cb0c — MSRC update guide not readable via web-cli (empty); fixed builds taken from OffSeq relay of Microsoft's CNA record, so nothing marked verified. UI:R per CVSS vector: victim must open a crafted file. Re-check on MSRC page.

## Documents

- [describes] OffSeq: CVE-2026-124176 (relays Microsoft CNA record) https://radar.offseq.com/threat/cve-2026-124176-cwe-122-heap-based-buffer-overflow-in-microsoft-microsoft-365-apps-for-enterprise-103cee1e9408cb0c

## 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_