CVE-2026-31834

High

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.

SeverityHigh

CVSS7.2

Exploit probability—

Product

Umbraco Cms

PublishedMar 10, 2026

First seenMar 10, 2026

Weakness typeCWE-269Improper privilege management CWE-284Improper access control CWE-862Missing authorization

How to fix

Update

umbraco umbraco_cms16.5.1, 17.2.2 or later
Umbraco.Cms16.5.1, 17.2.2 or later

Affected products

Product	Affected versions	Fixed in
umbraco umbraco_cms	15.3.1 ≤ v < 16.5.1, 17.0.0 ≤ v < 17.2.2	16.5.1, 17.2.2
Umbraco.CmsNuGet	15.3.1 ≤ v < 16.5.1, 17.0.0 ≤ v < 17.2.2	16.5.1, 17.2.2

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