CVE-2026-111624
CVE-2026-111624 · Umbraco CMS before 17.7.1 and 18.2.1 Missing Authorization on SignalR Hubs
This page contains facts from public vulnerability sources. Check the original advisory before updating.
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can complete the SignalR negotiate step and receive refreshed notifications that disclose content keys, including unpublished content, and reveal editorial activity timing.
CVSS 6.3 · Medium · EPSS 0.3% · Fix available
- Published
- Updated
Affected products and versions
umbraco-cms
- Versions
- ≥ 17.0.0, < 17.7.1: Affected (semver)
- ≥ 18.0.0, < 18.2.1: Affected (semver)
Update to 17.7.1; Update to 18.2.1
Original sources
- https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-4c5q-6c64-96j7
- https://github.com/umbraco/Umbraco-CMS/blob/release-18.2.0/src/Umbraco.Cms.Api.Management/Preview/PreviewHub.cs#L9-L11
- https://github.com/umbraco/Umbraco-CMS/blob/release-18.2.0/src/Umbraco.Cms.Api.Management/Preview/PreviewHubUpdater.cs#L58
- https://github.com/umbraco/Umbraco-CMS/commit/b4f6cfc9d0955f9d8443e68353db4a692e91bd94
- https://github.com/umbraco/Umbraco-CMS/commit/243e082479c777d0f585bbd2f8db571607767b22
- https://github.com/umbraco/Umbraco-CMS/releases/tag/release-18.2.1
- https://github.com/umbraco/Umbraco-CMS/releases/tag/release-17.7.1
- https://www.vulncheck.com/advisories/umbraco-cms-before-17.7.1-and-18.2.1-missing-authorization-on-signalr-hubs
- https://nvd.nist.gov/vuln/detail/CVE-2026-111624