Privilege Escalation Vulnerability in Umbraco CMS by Umbraco
CVE-2026-31834

7.2HIGH

Key Information:

Vendor

Umbraco

Status
Umbraco-cms
Vendor
CVE Published:
10 March 2026

What is CVE-2026-31834?

Umbraco, a widely used ASP.NET CMS, contains a privilege escalation vulnerability that affects authenticated backoffice users with user management permissions. This issue originates from inadequate authorization checks during the modification of user group memberships, allowing users to potentially elevate their privileges beyond their intended access level. The flaw exists in Umbraco CMS versions from 15.3.1 up to but not including 16.5.1, as well as 17.2.2. This vulnerability poses a significant risk, especially for organizations relying on Umbraco for content management. Mitigation is achievable by updating to the latest versions, 16.5.1 or 17.2.2, where the issue has been resolved.

Affected Version(s)

Umbraco-CMS >= 15.3.1, < 16.5.1 < 15.3.1, 16.5.1

Umbraco-CMS >= 17.0.0, < 17.2.1 < 17.0.0, 17.2.1

References

https://github.com/umbraco/Umbraco-CMS/security/advisorie...
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CVSS V3.1

Score:
7.2
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
High
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.