CVE-2026-111624

EUVD-2026-103046
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can complete the SignalR negotiate step and receive refreshed notifications that disclose content keys, including unpublished content, and reveal editorial activity timing.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
3.7 LOW
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 22.47%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
umbracoumbraco
17.0.0 ≤
𝑥
< 17.7.1
CNA
umbracoumbraco
18.0.0 ≤
𝑥
< 18.2.1
CNA
Common Weakness Enumeration
References
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/243e082479c777d0f585bbd2f8db571607767b22
https://github.com/umbraco/Umbraco-CMS/commit/b4f6cfc9d0955f9d8443e68353db4a692e91bd94
https://github.com/umbraco/Umbraco-CMS/releases/tag/release-17.7.1
https://github.com/umbraco/Umbraco-CMS/releases/tag/release-18.2.1
https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-4c5q-6c64-96j7
https://www.vulncheck.com/advisories/umbraco-cms-before-17.7.1-and-18.2.1-missing-authorization-on-signalr-hubs