CVE-2026-3241Network attack vector

Viewer-side script execution via unescaped form options

Published Mar 4, 2026 · Updated Mar 4, 2026

Stored XSS in the Legacy Form block in Concrete CMS before 9.4.8 allows remote authenticated users to execute JavaScript in viewers' browsers. The loadInputType method in concrete/blocks/form/mini_survey.php inserts stored checkbox, radio, and select option text into HTML without encoding it. Form-creation or editing permission is required, and the payload runs when another user views a page containing the crafted form.

CVSS severity4.8
Medium
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in the Legacy Form block in Concrete CMS before 9.4.8 allows remote authenticated users to execute JavaScript in viewers' browsers. The loadInputType method in concrete/blocks/form/mini_survey.php inserts stored checkbox, radio, and select option text into HTML without encoding it. Form-creation or editing permission is required, and the payload runs when another user views a page containing the crafted form.

The record

CVE
CVE-2026-3241
Published
Mar 4, 2026
Updated
Mar 4, 2026
Vendor
Concrete CMS
Product
Concrete CMS
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5 <9.4.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Concrete CMS · Concrete CMSversion=5 <9.4.8

Published CVSS scores

4.8ConcreteCMSCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
4.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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