---
id: "CVE-2026-109494"
page: "https://infrastack.ai/live/CVE-2026-109494"
kind: "vulnerability"
aliases: ["CVE-2026-109494"]
title: "Microsoft Office Visio: heap overflow lets a network attacker run code"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "other"
products: [{"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 365 Apps for Enterprise", "fixed": [], "affected": ">= 16.0.1, fixed build per aka.ms/OfficeSecurityReleases", "ecosystem": "vendor"}]
ecosystems: []
tags: ["microsoft-office", "other", "rce", "visio", "windows"]
not_affected_if: ["visio-not-installed"]
published_at: "2026-11-10T19:18:18+00:00"
first_seen_at: "2026-11-10T19:24:25+00:00"
updated_at: "2026-11-11T00:43:05+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109494", "first_seen_at": "2026-11-10T19:24:25+00:00"}, {"source": "analyst", "url": "https://app.opencve.io/cve/CVE-2026-109494", "first_seen_at": "2026-11-11T00:43:05+00:00", "cites": ["https://app.opencve.io/cve/CVE-2026-109494", "https://www.zerodayinitiative.com/blog/2026/11/10/the-november-2026-security-update-review"]}]
exploit_sources: []
---

# Microsoft Office Visio: heap overflow lets a network attacker run code

Link for people: https://infrastack.ai/live/CVE-2026-109494 (this .md is for agents)

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

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

## Affected

- 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 365 Apps for Enterprise affected >= 16.0.1, fixed build per aka.ms/OfficeSecurityReleases fixed no fixed version listed

## How to check

In any Office app open File > Account and read the version and build. Compare with the fixed build: LTSC 2021 16.0.14334.21048, LTSC 2024 16.0.17932.21140, Microsoft 365 Apps per https://aka.ms/OfficeSecurityReleases. Only matters if Visio is installed. Also check Visio 2019/2016 if you run them; the CNA record does not list them.

## Fix

Update Office to a build at or above: LTSC 2021 16.0.14334.21048; LTSC 2024 16.0.17932.21140; Microsoft 365 Apps: the build listed at https://aka.ms/OfficeSecurityReleases. Read from the CNA record, not confirmed on the MSRC page.

## Timeline

- 2026-11-10T19:24:25+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-109494
- 2026-11-11T00:43:05+00:00 analyst https://app.opencve.io/cve/CVE-2026-109494 — MSRC page is JS-only and could not be read; affected builds taken from Microsoft's CNA record as mirrored by OpenCVE/NVD. ZDI lists it Important, 8.8, not exploited, not public. Nothing verified.

## Documents

- [describes] OpenCVE: CVE-2026-109494 (mirrors Microsoft CNA record) https://app.opencve.io/cve/CVE-2026-109494
- [mentions] ZDI: November 2026 Security Update Review https://www.zerodayinitiative.com/blog/2026/11/10/the-november-2026-security-update-review

## From the sources

Heap-based buffer overflow in Microsoft Office Visio 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_