---
id: "CVE-2026-109491"
page: "https://infrastack.ai/live/CVE-2026-109491"
kind: "vulnerability"
aliases: ["CVE-2026-109491"]
title: "Microsoft Word: use-after-free lets a remote attacker run code"
severity: "high"
cvss: 7.5
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "Microsoft Office Word", "fixed": ["Current Channel 2610 20527.20196", "Office LTSC 2024 17932.21140", "Office LTSC 2021 14334.21048", "Office 2019 10417.20236"], "affected": "unknown lower bound; builds before Nov 10, 2026 updates", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["desktop", "microsoft-office", "package", "user-interaction", "word"]
not_affected_if: []
published_at: "2026-11-10T19:18:17+00:00"
first_seen_at: "2026-11-10T19:24:25+00:00"
updated_at: "2026-11-11T00:43:10+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109491", "first_seen_at": "2026-11-10T19:24:25+00:00"}, {"source": "analyst", "url": "https://www.zerodayinitiative.com/blog/2026/11/10/the-november-2026-security-update-review", "first_seen_at": "2026-11-11T00:43:10+00:00", "cites": ["https://www.zerodayinitiative.com/blog/2026/11/10/the-november-2026-security-update-review", "https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates"]}]
exploit_sources: []
---

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

Link for people: https://infrastack.ai/live/CVE-2026-109491 (this .md is for agents)

A use-after-free bug in Microsoft Office Word lets an unauthorized attacker run code over a network. The sources give a CVSS score of 7.5 and no fixed version.

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

## Affected

- vendor:Microsoft Office Word affected unknown lower bound; builds before Nov 10, 2026 updates fixed Current Channel 2610 20527.20196, Office LTSC 2024 17932.21140, Office LTSC 2021 14334.21048, Office 2019 10417.20236

## How to check

In Word open File > Account > About Word and compare the version/build with the fixed builds in the fix field; or run 'Update Options > Update Now'. Microsoft lists this CVE under Word in the Nov 10, 2026 release notes.

## Fix

Update Microsoft 365 Apps / Office to the Nov 10, 2026 builds or later: 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 2408 (17932.21140); LTSC 2021 2108 (14334.21048); Office 2019 1808 (10417.20236).

## Timeline

- 2026-11-10T19:24:25+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-109491
- 2026-11-11T00:43:10+00:00 analyst https://www.zerodayinitiative.com/blog/2026/11/10/the-november-2026-security-update-review — MSRC page is JS-only and unreadable; fix builds from Microsoft Office release notes (Nov 10, 2026) listing the CVE under Word. ZDI: not exploited, not public. Vector AC:H/UI:R. Affected lower bounds unknown; MSRC page would settle it.

## Documents

- [describes] ZDI: November 2026 Security Update Review https://www.zerodayinitiative.com/blog/2026/11/10/the-november-2026-security-update-review
- [fix] Microsoft Office security updates release notes (Nov 10, 2026) https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates

## From the sources

Use after free in Microsoft Office Word 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_