High severityNVD Advisory· Published Mar 10, 2026· Updated Mar 11, 2026
Umbraco Affected by Vertical Privilege Escalation via Missing Authorization Checks
CVE-2026-31834
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.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
Umbraco.CmsNuGet | >= 15.3.1, < 16.5.1 | 16.5.1 |
Umbraco.CmsNuGet | >= 17.0.0, < 17.2.2 | 17.2.2 |
Affected products
1- Range: >= 15.3.1, < 16.5.1
Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
3- github.com/advisories/GHSA-rhcg-3h8r-v6vpghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-31834ghsaADVISORY
- github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-rhcg-3h8r-v6vpghsax_refsource_CONFIRMWEB
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