CVE-2026-31833
Umbraco has Stored XSS in UFM Rendering Pipeline via Permissive DOMPurify Attribute Filtering
CVSS Score
6.7
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-79 |
| Vendor | umbraco |
| Product | umbraco-cms |
| Published | Mar 10, 2026 |
| Last Updated | Mar 11, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
Low
Affected Versions
umbraco / Umbraco-CMS
>= 16.2.0, < 16.5.1 >= 17.0.0, < 17.2.1