CVE-2026-31834 HIGH

CVE-2026-31834: Umbraco Affected by Vertical Privilege Escalation via Missing Authorization Checks

Vendor Umbraco
Product Umbraco-CMS
Weakness CWE-269
Published March 10, 2026
Last update March 11, 2026

CVSS base score

7.2/10
Attack vector Network
Attack complexity Low
Privileges required High
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

What the vulnerability does

01Description

Umbraco is an ASP.NET CMS. From 15.3.1 to before 16.5.1 and 17.2.2, A privilege escalation vulnerability has been identified in Umbraco CMS. Under certain conditions, authenticated backoffice users with permission to manage users, may be able to elevate their privileges due to insufficient authorization enforcement when modifying user group memberships. The affected functionality does not properly validate whether a user has sufficient privileges to assign highly privileged roles. This vulnerability is fixed in 16.5.1 and 17.2.2.

Key dates

02Disclosure timeline

March 10, 2026 CVE published
March 11, 2026 Record updated