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Low severity · published Oct 16, 2026
CVE-2026-111624
Umbraco CMS before 17.7.1 and 18.2.1 Missing Authorization on SignalR Hubs
3.7
CVSS
0.3%
EPSS
No
On KEV
Description
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can complete the SignalR negotiate step and receive refreshed notifications that disclose content keys, including unpublished content, and reveal editorial activity timing.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 vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
UM
Umbraco-CMS · umbraco
17.0.0 before 17.7.1; 18.0.0 before 18.2.1 · source: vendor
Affected product
UM
Umbraco-CMS
umbraco
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-111624
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-111624
github.com
https://github.com/umbraco/Umbraco-CMS/blob/release-18.2.0/src/Umbraco.Cms.Api.Management/Preview/PreviewHub.cs#L9-L11
github.com
https://github.com/umbraco/Umbraco-CMS/blob/release-18.2.0/src/Umbraco.Cms.Api.Management/Preview/PreviewHubUpdater.cs#L58
github.com
https://github.com/umbraco/Umbraco-CMS/commit/243e082479c777d0f585bbd2f8db571607767b22
github.com
https://github.com/umbraco/Umbraco-CMS/commit/b4f6cfc9d0955f9d8443e68353db4a692e91bd94
github.com
https://github.com/umbraco/Umbraco-CMS/releases/tag/release-17.7.1
github.com
https://github.com/umbraco/Umbraco-CMS/releases/tag/release-18.2.1
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