Missing Authorization in Umbraco CMS - CVE-2026-31834
Published: May 5, 2026
Vulnerability identifier: #VU130189
CSH Severity: Low
CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-31834
CWE-ID: CWE-862
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to escalate privileges.
The vulnerability exists due to missing authorization in user group membership management functionality when modifying user group memberships. A remote privileged user can assign highly privileged roles to escalate privileges.
Exploitation requires access to the "Users" section in the backoffice.
Affected software
Umbraco CMS
How to mitigate CVE-2026-31834
Install security update from vendor's website.
Umbraco CMS - addressed in versions 16.5.1, 17.2.2