CVE-2026-31833 — Umbraco has Stored XSS in UFM Rendering Pipeline via Permissive DOMPurify Attribute Filtering

CVE-2026-31833

Umbraco has Stored XSS in UFM Rendering Pipeline via Permissive DOMPurify Attribute Filtering PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / product	Versions
umbraco / Umbraco-CMS	affected >= 16.2.0, < 16.5.1; affected >= 17.0.0, < 17.2.1

CWE

CWE-79

References

https://github.com/umbraco/Umbraco-CMS/security/advisories/GHSA-vrqc-59mw-qqg7

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.