CVE Tools
Sign in

CVE-2026-31833

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

Published: Mar 10, 2026Updated: Mar 18, 2026 Sources: CVE List NVDCWE-79
NVD MITRE
6.7CVSSMEDIUM
EPSS Score
0.3%
Top 82.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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 Vector Breakdown

AV:NAC:LPR:HUI:NS:UC:HI:HA:L
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:HPrivileges Required
High
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:LAvailability
Low
Open in CVSS calculator →

Weaknesses

CWE-79

Affected Products

Umbraco-CMSumbraco
On-premCMS Plugin
Web & CMS Plugins / cms-core
umbraco cmsumbraco
On-premCMS Plugin
Web & CMS Plugins / cms-core
umbracocommercialDKWeb & CMS Pluginsaka umbraco cms, umbraco forms, umbraco-cms

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

Official Patch Available

MITRE ATT&CK

2 techniques
Execution
Initial Access
View detailed technique mapping

References

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

Timeline

Published
Mar 10, 2026
Last Updated
Mar 18, 2026

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2026-31833 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows