CVE-2026-3240: Concretecms Concrete CMS

Medium severity, CVSS 4.8. EPSS: 0.3% chance of exploitation in the next 30 days.

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.

Affected products

• Concretecms Concrete CMS: before 9.4.8 (fixed in 9.4.8)

Published 2026-03-04. Last modified 2026-06-17.