CVE-2026-3240
Concrete CMS has a stored Cross-site Scripting (XSS) vulnerability
EPSS 0.01%
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 thanks minhnn42, namdi and quanlna2 from VCSLab-Viettel Cyber Security for reporting.
How to fix CVE-2026-3240
To remediate CVE-2026-3240, upgrade the affected package to a fixed version below.
- Packagist/concrete5/concrete5—upgrade to 9.4.8 or later
Is CVE-2026-3240 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 9.4.8
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |