---
id: "CVE-2026-118296"
page: "https://infrastack.ai/live/CVE-2026-118296"
kind: "vulnerability"
aliases: ["CVE-2026-118296"]
title: "Microsoft Excel double free: opening a crafted file can run code (fixed in Nov 2026 update)"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "Microsoft Office Excel", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "Microsoft 365 Apps for Enterprise", "fixed": ["Current Channel 2610 20527.20196"], "affected": ">= 16.0.1, before Nov 10 2026 builds (see release notes)", "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 for Mac", "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", "office-online-server", "package", "user-interaction", "windows"]
not_affected_if: []
published_at: "2026-11-10T19:19:43+00:00"
first_seen_at: "2026-11-10T19:24:52+00:00"
updated_at: "2026-11-10T23:12:52+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-118296", "first_seen_at": "2026-11-10T19:24:52+00:00"}, {"source": "analyst", "url": "https://app.opencve.io/cve/CVE-2026-118296", "first_seen_at": "2026-11-10T23:12:52+00:00", "cites": ["https://app.opencve.io/cve/CVE-2026-118296", "https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates", "https://www.action1.com/patch-tuesday/patch-tuesday-november-2026/"]}]
exploit_sources: []
---

# Microsoft Excel double free: opening a crafted file can run code (fixed in Nov 2026 update)

Link for people: https://infrastack.ai/live/CVE-2026-118296 (this .md is for agents)

A double free bug in Microsoft Office Excel lets an unauthorized attacker run code over a network. The sources give no further detail on how a file or message triggers it.

_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 >= 16.0.1, before Nov 10 2026 builds (see release notes) fixed Current Channel 2610 20527.20196
- 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 for Mac 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 Excel and compare the version/build with the fixed builds. Fleet: check Office ClickToRun VersionToReport in HKLM\SOFTWARE\Microsoft\Office\ClickToRun\Configuration; on Mac, Excel version below 16.115.26110837 is affected.

## Fix

Update Office to the Nov 10, 2026 builds or later: Microsoft 365 Apps Current Channel 2610 build 20527.20196 (Monthly Enterprise 2610 20527.20194, 2609 20430.20264, 2608 20326.20320; Semi-Annual 2610 20527.20192, 2609 20430.20262, 2608 20326.20318); Office LTSC 2024 build 17932.21140; Office LTSC 2021 build 14334.21048. Mac (Microsoft 365, LTSC 2021/2024 for Mac): 16.115.26110837 per the CNA record. Office Online Server: CNA lists fixed below 16.0.10417.20236.

## Timeline

- 2026-11-10T19:24:52+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-118296
- 2026-11-10T23:12:52+00:00 analyst https://app.opencve.io/cve/CVE-2026-118296 — Fix builds from Microsoft Learn Office security release notes (Nov 10 2026, lists CVE under Excel); affected ranges from Microsoft CNA record via OpenCVE (MSRC page is JS-only, not read). Not exploited, no public PoC per Action1/CNA E:U. UI:R per CVSS vector.

## Documents

- [describes] OpenCVE: CVE-2026-118296 (Microsoft CNA affected versions) https://app.opencve.io/cve/CVE-2026-118296
- [fix] Microsoft Office security updates release notes (Nov 10, 2026) https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
- [mentions] Patch Tuesday November 2026 (Action1) https://www.action1.com/patch-tuesday/patch-tuesday-november-2026/

## From the sources

Double free 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_