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

TRUNG BÌNH 6.7CVE-2026-31833 · GHSA-vrqc-59mw-qqg7 · Công bố 10/03/2026 · cập nhật 17/06/2026

Tóm tắt nhanh

CVE-2026-31833 là lỗ hổng mức TRUNG BÌNH (CVSS 6.7) ảnh hưởng Umbraco.Cms, umbraco cms (umbraco).
Xác suất bị khai thác trong 30 ngày tới (EPSS): 0.28%, cao hơn 20.1% các lỗ hổng khác.
Cách xử lý: cập nhật lên 16.5.1, 17.2.2 hoặc mới hơn.

Gói / sản phẩm	Phiên bản bị ảnh hưởng	Phiên bản đã vá
Umbraco.Cms NuGet	`≥ 16.2.0, < 16.5.1≥ 17.0.0, < 17.2.2`	`16.5.117.2.2`
umbraco cms umbraco	`≥ 16.2.0, < 16.5.1≥ 17.0.0, < 17.2.2`	`16.5.117.2.2`

Mô tả

Description

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.

Impact

As property type descriptions support Markdown/HTML via the UFM rendering pipeline, injected event handlers are rendered in the backoffice interface, resulting in a stored XSS affecting other backoffice users.

Patches

The issue is patched in 16.5.1 and 17.2.2.

Workarounds

There is no workaround other than upgrading.

References

https://docs.umbraco.com/umbraco-cms/reference/umbraco-flavored-markdown

Mô tả của NVD

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.