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Medium · 4.8 CVE-2026-3241 EUVD-2026-9359GHSA-f4vq-pj32-gr4q

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

Published Mar 4, 2026 · Updated Mar 4, 2026 · Assigned by ConcreteCMS

Description

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.

Affected products

VendorProductAffectedFixed
Concrete CMS Concrete CMS — —

Affected packages

EcosystemPackageAffectedFixedRecord
Packagist concrete5/concrete5 < 9.4.8 9.4.8 GHSA-f4vq-pj32-gr4q

References