CVE-2026-3240
Received Received - Intake
Stored XSS in Concrete CMS Legacy Form Affects High-Privilege Users

Publication date: 2026-03-04

Last updated on: 2026-03-04

Assigner: ConcreteCMS

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 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.
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Meta Information
Published
2026-03-04
Last Modified
2026-03-04
Generated
2026-06-16
AI Q&A
2026-03-04
EPSS Evaluated
2026-06-15
NVD
CVE-2026-3240
EUVD
EUVD-2026-9358
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
concretecms concrete_cms to 9.4.8 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-79 The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
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Executive Summary

This vulnerability exists in Concrete CMS versions below 9.4.8. It allows a user who has permission to edit a page containing the Legacy form element to perform a stored Cross-Site Scripting (XSS) attack. The attack is executed via the 'Question' field and targets high-privilege accounts, potentially compromising their security.

Impact Analysis

The vulnerability can impact you by enabling an attacker with certain editing permissions to inject malicious scripts that are stored and later executed in the context of high-privilege users. This can lead to unauthorized actions performed by those high-privilege accounts, potentially compromising the integrity and security of your Concrete CMS installation.

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