CVE-2026-31833

Description

Umbraco is an ASP.NET CMS. From 16.2.0 to before 16.5.1 and 17.2.2, An authenticated backoffice user with access to Settings can inject malicious HTML into property type descriptions. Due to an overly permissive attributeNameCheck configuration (/.+/) in the UFM DOMPurify instance, event handler attributes such as onclick and onload, when used within Umbraco web components (umb-*, uui-*, ufm-*) were not filtered. 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

Problem types

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Product status

References

github.com/...co-CMS/security/advisories/GHSA-vrqc-59mw-qqg7

cve.org (CVE-2026-31833)

nvd.nist.gov (CVE-2026-31833)

Download JSON