Low 3.7Published Oct 16, 2026

CVE-2026-111624Umbraco CMS before 17.7.1 and 18.2.1 Missing Authorization on SignalR Hubs

Updated under an hour ago (Oct 28, 2026, 8:30 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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can complete the SignalR negotiate step and receive refreshed notifications that disclose content keys, including unpublished content, and reveal editorial activity timing.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: 3.7 LOW (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness (CWE): CWE-306
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: VulnCheck
NVD analysis: Awaiting Analysis
Record last updated: Oct 21, 2026
First seen by InfoSec Signals: Oct 16, 2026

Affected products

Affected products

umbraco Umbraco-CMS umbraco:cms (from the name)	from 17.0.0 before 17.7.1; from 18.0.0 before 18.2.1	CNA record

References

References

https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-4c5q-6c64-96j7	vendor-advisory
https://github.com/umbraco/Umbraco-CMS/blob/release-18.2.0/src/Umbraco.Cms.Api.Management/Preview/PreviewHub.cs#L9-L11	technical-description
https://github.com/umbraco/Umbraco-CMS/blob/release-18.2.0/src/Umbraco.Cms.Api.Management/Preview/PreviewHubUpdater.cs#L58	technical-description
https://github.com/umbraco/Umbraco-CMS/commit/b4f6cfc9d0955f9d8443e68353db4a692e91bd94	patch
https://github.com/umbraco/Umbraco-CMS/commit/243e082479c777d0f585bbd2f8db571607767b22	patch
https://github.com/umbraco/Umbraco-CMS/releases/tag/release-18.2.1	release-notes
https://github.com/umbraco/Umbraco-CMS/releases/tag/release-17.7.1	release-notes
https://www.vulncheck.com/advisories/umbraco-cms-before-17.7.1-and-18.2.1-missing-authorization-on-signalr-hubs	third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.