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Description

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.

PUBLISHED Reserved 2026-03-09 | Published 2026-03-10 | Updated 2026-03-11 | Assigner GitHub_M




HIGH: 7.2CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Problem types

CWE-269: Improper Privilege Management

CWE-284: Improper Access Control

CWE-862: Missing Authorization

Product status

>= 15.3.1, < 16.5.1
affected

>= 17.0.0, < 17.2.1
affected

References

github.com/...co-CMS/security/advisories/GHSA-rhcg-3h8r-v6vp

cve.org (CVE-2026-31834)

nvd.nist.gov (CVE-2026-31834)

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