---
id: CVE-2026-111624
title: Umbraco CMS before 17.7.1 and 18.2.1 Missing Authorization on SignalR Hubs
summary: >-
  Umbraco CMS before 17.7.1 and 18.2.1 contains a missing authorization
  vulnerability that allows unauthenticated clients to connect to the backoffice
  PreviewHub and BackofficeHub SignalR hubs. Attackers can complete the SignalR
  negotiate …
severity: low
cvss: 3.7
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-306
vendor: umbraco
product: Umbraco-CMS
affected:
  - Umbraco-CMS >= 17.0.0 < 17.7.1
  - Umbraco-CMS >= 18.0.0 < 18.2.1
published: '2026-10-16'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T17:39:00.093Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-111624'
references:
  - url: >-
      https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-4c5q-6c64-96j7
    label: GitHub Security Advisory (GHSA-4c5q-6c64-96j7)
  - url: >-
      https://github.com/umbraco/Umbraco-CMS/blob/release-18.2.0/src/Umbraco.Cms.Api.Management/Preview/PreviewHub.cs#L9-L11
  - url: >-
      https://github.com/umbraco/Umbraco-CMS/blob/release-18.2.0/src/Umbraco.Cms.Api.Management/Preview/PreviewHubUpdater.cs#L58
  - url: >-
      https://github.com/umbraco/Umbraco-CMS/commit/b4f6cfc9d0955f9d8443e68353db4a692e91bd94
  - url: >-
      https://github.com/umbraco/Umbraco-CMS/commit/243e082479c777d0f585bbd2f8db571607767b22
  - url: 'https://github.com/umbraco/Umbraco-CMS/releases/tag/release-18.2.1'
    label: Umbraco-CMS release-18.2.1 Release Notes
  - url: 'https://github.com/umbraco/Umbraco-CMS/releases/tag/release-17.7.1'
    label: Umbraco-CMS release-17.7.1 Release Notes
  - url: >-
      https://www.vulncheck.com/advisories/umbraco-cms-before-17.7.1-and-18.2.1-missing-authorization-on-signalr-hubs
    label: >-
      VulnCheck Advisory: Umbraco CMS before 17.7.1 and 18.2.1 Missing
      Authorization on SignalR Hubs
tags:
  - cve.org
ingestedAt: '2026-10-16T18:43:08.690Z'
---

## Overview

Umbraco CMS before 17.7.1 and 18.2.1 contains a missing authorization vulnerability that allows unauthenticated clients to connect to the backoffice PreviewHub and BackofficeHub SignalR hubs. Attackers can complete the SignalR negotiate step and receive refreshed notifications that disclose content keys, including unpublished content, and reveal editorial activity timing.

## Affected

- `Umbraco-CMS >= 17.0.0 < 17.7.1`
- `Umbraco-CMS >= 18.0.0 < 18.2.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.