---
id: "CVE-2026-118705"
page: "https://infrastack.ai/live/CVE-2026-118705"
kind: "vulnerability"
aliases: ["CVE-2026-118705"]
title: "Microsoft Excel: heap overflow lets an unauthorized attacker run code remotely"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "other"
products: [{"name": "Microsoft 365 Apps for Enterprise", "fixed": [], "affected": ">= 16.0.1, fixed build per channel at aka.ms/OfficeSecurityReleases", "ecosystem": "vendor"}, {"name": "Microsoft Office LTSC 2021", "fixed": ["16.0.14334.21048"], "affected": ">= 16.0.1, < 16.0.14334.21048", "ecosystem": "vendor"}, {"name": "Microsoft Office LTSC 2024", "fixed": ["16.0.17932.21140"], "affected": ">= 16.0.0, < 16.0.17932.21140", "ecosystem": "vendor"}, {"name": "Microsoft Office 365 for Mac", "fixed": ["16.115.26110837"], "affected": "< 16.115.26110837", "ecosystem": "vendor"}, {"name": "Microsoft Office LTSC for Mac 2021", "fixed": ["16.115.26110837"], "affected": ">= 16.0.1, < 16.115.26110837", "ecosystem": "vendor"}, {"name": "Microsoft Office LTSC for Mac 2024", "fixed": ["16.115.26110837"], "affected": ">= 16.0.0, < 16.115.26110837", "ecosystem": "vendor"}, {"name": "Office Online Server", "fixed": ["16.0.10417.20236"], "affected": ">= 16.0.0.0, < 16.0.10417.20236", "ecosystem": "vendor"}]
ecosystems: []
tags: ["excel", "macos", "microsoft-office", "other", "user-interaction", "windows"]
not_affected_if: ["managed-hosting", "patched-build"]
published_at: "2026-11-10T19:19:45+00:00"
first_seen_at: "2026-11-10T19:24:52+00:00"
updated_at: "2026-11-10T23:10:34+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-118705", "first_seen_at": "2026-11-10T19:24:52+00:00"}, {"source": "analyst", "url": "https://nvd.nist.gov/vuln/detail/cve-2026-118705", "first_seen_at": "2026-11-10T23:10:34+00:00", "cites": ["https://nvd.nist.gov/vuln/detail/cve-2026-118705", "https://app.opencve.io/cve/CVE-2026-118705"]}]
exploit_sources: []
---

# Microsoft Excel: heap overflow lets an unauthorized attacker run code remotely

Link for people: https://infrastack.ai/live/CVE-2026-118705 (this .md is for agents)

Heap-based buffer overflow in Microsoft Office Excel (CWE-122). Microsoft rates it 8.8 High (CVSS 3.1, network, no privileges, user interaction required): an attacker needs a victim to open a crafted file, then can run code as that user. Microsoft's record shows no exploitation as of publication on 2026-11-10.

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

## Affected

- vendor:Microsoft 365 Apps for Enterprise affected >= 16.0.1, fixed build per channel at aka.ms/OfficeSecurityReleases fixed no fixed version listed
- vendor:Microsoft Office LTSC 2021 affected >= 16.0.1, < 16.0.14334.21048 fixed 16.0.14334.21048
- vendor:Microsoft Office LTSC 2024 affected >= 16.0.0, < 16.0.17932.21140 fixed 16.0.17932.21140
- vendor:Microsoft Office 365 for Mac affected < 16.115.26110837 fixed 16.115.26110837
- vendor:Microsoft Office LTSC for Mac 2021 affected >= 16.0.1, < 16.115.26110837 fixed 16.115.26110837
- vendor:Microsoft Office LTSC for Mac 2024 affected >= 16.0.0, < 16.115.26110837 fixed 16.115.26110837
- vendor:Office Online Server affected >= 16.0.0.0, < 16.0.10417.20236 fixed 16.0.10417.20236

## How to check

In Excel, File > Account > About Excel and compare the build with the fixed builds. For Microsoft 365 Apps, see https://aka.ms/OfficeSecurityReleases for the fixed build per channel. Fixed: LTSC 2021 16.0.14334.21048, LTSC 2024 16.0.17932.21140, Office for Mac 16.115.26110837, Office Online Server 16.0.10417.20236.

## Fix

Update to: Office LTSC 2021 16.0.14334.21048 or later; LTSC 2024 16.0.17932.21140 or later; Office 365/LTSC 2021/2024 for Mac 16.115.26110837 or later; Office Online Server 16.0.10417.20236 or later; Microsoft 365 Apps: the build in the Office security release notes for your channel.

## Timeline

- 2026-11-10T19:24:52+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-118705
- 2026-11-10T23:10:34+00:00 analyst https://nvd.nist.gov/vuln/detail/cve-2026-118705 — MSRC page is JS-only (did not render); data taken from Microsoft's CNA record as mirrored by NVD/OpenCVE. Nothing marked verified. No exploitation or PoC seen (not in KEV). CVSS UI:R so a file must be opened.

## Documents

- [describes] NVD CVE-2026-118705 (carries Microsoft CNA record) https://nvd.nist.gov/vuln/detail/cve-2026-118705
- [mentions] OpenCVE CVE-2026-118705 (CNA record mirror) https://app.opencve.io/cve/CVE-2026-118705

## 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_