What is the CVSS score of CVE-2026-3240?

CVE-2026-3240 has a CVSS 3.1 base score of 4.8 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of Concrete Cms are affected by CVE-2026-3240?

Organizations using Concrete CMS below should be aware of moderate risk from CVE-2026-3240, a cross-site scripting vulnerability rated CVSS 4.8.. A patch is available.

Is there a public PoC exploit available for CVE-2026-3240?

Yes, a public proof-of-concept exploit is available for CVE-2026-3240. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-3240?

Within 30 days: Identify affected systems running Concrete CMS below and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Concrete Cms CVE-2026-3240

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-03-04 ff5b8ace-8b95-4078-9743-eac1ca5451de

GHSA-45fj-fvmm-xcc5

XSS Concrete Cms

4.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

4.8 MEDIUM

AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

High

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 22:05 vuln.today

PoC Detected

Mar 04, 2026 - 21:32 vuln.today

Public exploit code

Patch released

Mar 04, 2026 - 21:32 nvd

Patch available

CVE Published

Mar 04, 2026 - 03:16 nvd

MEDIUM 4.8

DescriptionCVE.org

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.

AnalysisAI

Stored XSS in Concrete CMS versions before 9.4.8 allows authenticated users with page editing permissions to inject malicious scripts through the Legacy form Question field, targeting high-privilege accounts. Public exploit code exists for this vulnerability, which requires user interaction to execute. A patch is available in version 9.4.8 and later.

Technical ContextAI

Classified as CWE-79 (Cross-site Scripting (XSS)). Affects Concrete Cms. 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.

RemediationAI

A vendor patch is available — apply it immediately. Implement output encoding and Content Security Policy headers. Restrict network access to the affected service where possible.