CVE-2026-3240
MEDIUM
GHSA-45fj-fvmm-xcc5
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
Lifecycle Timeline
4Tags
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.
Analysis
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. …
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Remediation
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.
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External POC / Exploit Code
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