CVE-2026-3240CWE-79

Concrete CMS below 9.4.8 is vulnerable to Stored XSS via Legacy form

Medium · published March 4, 2026

CVSS v4.0
4.8
EPSS
0%
Percentile
19.8
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
4.8 · MEDIUM
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
EPSS
0.00284 · 19.8th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-03-04T02:15Z
EPSS history
Timeline
  • 04 MAR 02:15Z
    Concrete CMS below 9.4.8 is vulnerable to Stored XSS via Legacy form
    cvelistv5