Is CVE-2026-31833 in the CISA KEV catalog?

No. CVE-2026-31833 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-31833?

CVE-2026-31833 has a CVSS v3 base score of 6.7 (MEDIUM).

What is the EPSS score for CVE-2026-31833?

CVE-2026-31833 has an EPSS score of 0.26% (17th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-31833?

Upgrade umbraco cms to 17.2.2 or later.

CVE & CISA-KEV Catalog

CVE-2026-31833

MEDIUM

6.7

CVSS v3

NVD

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

umbraco cmsNVD

Affected:>= 17.0.0, < 17.2.2Fixed in:17.2.2CVE-2026-31833derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredHigh

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityLow

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L

Exploit Intelligence

0.26%probability of exploitation in 30 days

17thpercentile

Low risk: more likely to be exploited than 17% of all known CVEs.

References

Vendor Advisory1

github.com

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-11022	Medium	6.9	99%	-	Fix
CVE-2019-3929	Critical	9.8	99%	KEV	Fix
CVE-2020-9496	Medium	6.1	99%	-	-
CVE-2023-28341	Medium	6.1	99%	-	Fix
CVE-2018-12998	Medium	6.1	98%	-	-
CVE-2025-4123	High	7.6	98%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-18.