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OpenAdvisories
Medium · 6.7 CVE-2026-31833 EUVD-2026-10936GHSA-vrqc-59mw-qqg7

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

Published Mar 10, 2026 · Updated Mar 11, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
umbraco Umbraco-CMS >= 16.2.0, < 16.5.1, >= 17.0.0, < 17.2.1 —

Affected packages

EcosystemPackageAffectedFixedRecord
NuGet Umbraco.Cms >= 16.2.0, < 16.5.1 16.5.1 GHSA-vrqc-59mw-qqg7
NuGet Umbraco.Cms >= 17.0.0, < 17.2.2 17.2.2 GHSA-vrqc-59mw-qqg7

References