Is CVE-2026-3240 in the CISA KEV catalog?

No. CVE-2026-3240 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-3240?

CVE-2026-3240 has a CVSS v3 base score of 4.8 (MEDIUM).

What is the EPSS score for CVE-2026-3240?

CVE-2026-3240 has an EPSS score of 0.21% (12th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-3240?

Upgrade concrete cms to 9.4.8 or later.

CVE & CISA-KEV Catalog

CVE-2026-3240

MEDIUM

4.8

CVSS v3

NVD

Description

In Concrete CMS below version 9.4.8, a user with permission to edit a page with element Legacy form can perform a stored XSS attack towards high-privilege accounts via the Question field. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 4.8 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N Thanks minhnn42, namdi and quanlna2 from VCSLab-Viettel Cyber Security for reporting.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available

concrete cmsNVD

Affected:< 9.4.8Fixed in:9.4.8CVE-2026-3240derived 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 InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.21%probability of exploitation in 30 days

12thpercentile

Low risk: more likely to be exploited than 12% of all known CVEs.

References

Patch1

documentation.concretecms.org

Exploit1

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 2026-03-04.