CVE-2026-111624: Missing Authentication for Critical Function in umbraco Umbraco-CMS
Description
Umbraco CMS versions 17.0.0 through 17.7.0 and 18.0.0 through 18.2.0 have a missing authorization vulnerability. This flaw allows unauthenticated clients to connect to the backoffice PreviewHub and BackofficeHub SignalR hubs. Exploiting this, attackers can complete the SignalR negotiate step and receive notifications that disclose content keys, including unpublished content, and reveal editorial activity timing.
CVSS v4.0
Score 6.3medium
Affected software
umbraco
Umbraco-CMS
pkg:github/Umbraco-CMSRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-111624 describes a missing authentication vulnerability in Umbraco CMS before versions 17.7.1 and 18.2.1. The vulnerability permits unauthenticated clients to connect to the backoffice PreviewHub and BackofficeHub SignalR hubs. By completing the SignalR negotiate step, attackers can receive refreshed notifications that disclose sensitive content keys, including unpublished content, and reveal timing information about editorial activities. This exposure could lead to unauthorized information disclosure.
Potential Impact
The vulnerability allows unauthenticated attackers to obtain sensitive information such as unpublished content keys and editorial activity timing from the Umbraco CMS backoffice hubs. This could lead to information disclosure that may assist further attacks or unauthorized content access. There is no indication of privilege escalation or remote code execution. The CVSS 4.0 score is 6.3 (medium severity), reflecting the moderate impact of information disclosure without authentication.
Mitigation Recommendations
A fix is available in Umbraco CMS versions 17.7.1 and 18.2.1. Users should upgrade to these or later versions to remediate the vulnerability. No other mitigation or temporary workaround is indicated in the provided data.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-10-16T14:31:11.287Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ad2640d2cdf04f65619955b
Added to database: 10/16/2026, 17:51:09 UTC
Last enriched: 10/16/2026, 19:08:22 UTC
Last updated: 10/16/2026, 19:08:22 UTC
Views: 2
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