Medium 4.8Published Mar 3, 2026

CVE-2026-3241Concrete CMS below version 9.4.8 is vulnerable to a stored cross-site scripting (XSS) in the "Legacy Form" block.

Updated under an hour ago (Oct 26, 2026, 6:30 AM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

In Concrete CMS below version 9.4.8, a stored cross-site scripting (XSS) vulnerability exists in the "Legacy Form" block. An authenticated user with permissions to create or edit forms (e.g., a rogue administrator) can inject a persistent JavaScript payload into the options of a multiple-choice question (Checkbox List, Radio Buttons, or Select Box). This payload is then executed in the browser of any user who views the page containing the form. 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 M3dium for reporting.

CVSS: 4.8 MEDIUM (v4.0, CNA)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
Weakness (CWE): CWE-79
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: ConcreteCMS
NVD analysis: Analyzed
Record last updated: Mar 4, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Concrete CMS Concrete CMS concrete_cms:concrete_cms (from the name)	from 5 before 9.4.8	CNA record
concretecms concrete_cms concretecms:concrete_cms	before 9.4.8	NVD

References

https://github.com/concretecms/concretecms/pull/12826exploit, issue-tracking, vendor-advisory
https://documentation.concretecms.org/9-x/developers/introduction/version-history/948-release-notespatch, release-notes, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.