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

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
umbraco / Umbraco-CMS	affected >= 15.3.1, < 16.5.1; affected >= 17.0.0, < 17.2.1

CWE

CWE-269, CWE-284, CWE-862

References

https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-rhcg-3h8r-v6vp

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.