CVE-2026-31833
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.
Does this matter?
Lower severity and a low EPSS score (0.27%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 3.1
- 6.7 MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L
- EPSS
- 0.27% probability · 19th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Affected
- umbraco/umbraco cms
- Source
- security-advisories@github.com
EPSS 0.3% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.