---
id: "CVE-2026-109454"
page: "https://infrastack.ai/live/CVE-2026-109454"
kind: "vulnerability"
aliases: ["CVE-2026-109454"]
title: "Microsoft SharePoint: cross-site scripting lets an authorized user spoof pages"
severity: "critical"
cvss: 9.0
epss: null
exploited: false
status: "open"
category: "vendor"
products: [{"name": "Microsoft Office SharePoint", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "Microsoft SharePoint Server Subscription Edition", "fixed": ["16.0.20326.20278"], "affected": ">= 16.0.0, < 16.0.20326.20278", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["microsoft", "microsoft-office", "self-hosted", "sharepoint", "spoofing", "vendor", "xss"]
not_affected_if: ["managed-hosting"]
published_at: "2026-11-10T19:18:14+00:00"
first_seen_at: "2026-11-10T19:24:23+00:00"
updated_at: "2026-11-10T19:37:26+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109454", "first_seen_at": "2026-11-10T19:24:23+00:00"}, {"source": "analyst", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109454", "first_seen_at": "2026-11-10T19:37:26+00:00", "cites": ["https://nvd.nist.gov/vuln/detail/CVE-2026-109454"]}]
exploit_sources: []
---

# Microsoft SharePoint: cross-site scripting lets an authorized user spoof pages

Link for people: https://infrastack.ai/live/CVE-2026-109454 (this .md is for agents)

Microsoft Office SharePoint fails to neutralize input when generating web pages, a cross-site scripting flaw. An attacker with a valid account can perform spoofing over the network.

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

## Affected

- vendor:Microsoft Office SharePoint affected range not listed fixed no fixed version listed
- vendor:Microsoft SharePoint Server Subscription Edition affected >= 16.0.0, < 16.0.20326.20278 fixed 16.0.20326.20278

## How to check

In SharePoint Central Administration > Upgrade and Migration > Check product and patch installation status, or run (Get-SPFarm).BuildVersion in the SharePoint Management Shell; builds below 16.0.20326.20278 are affected.

## Fix

Update SharePoint Server Subscription Edition to build 16.0.20326.20278 or later (per Microsoft CNA data in NVD; confirm on the MSRC page).

## Timeline

- 2026-11-10T19:24:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-109454
- 2026-11-10T19:37:26+00:00 analyst https://nvd.nist.gov/vuln/detail/CVE-2026-109454 — MSRC page is JS-only and did not render; used NVD record carrying Microsoft CNA data (SharePoint Server Subscription Edition 16.0.0 < 16.0.20326.20278, CVSS 9.0 PR:L UI:R S:C). Nothing marked verified. No exploitation/PoC seen; social search skipped.

## Documents

- [describes] NVD: CVE-2026-109454 (Microsoft CNA data) https://nvd.nist.gov/vuln/detail/CVE-2026-109454

## From the sources

Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to perform spoofing 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_