Concrete Cms
CVE-2026-3242
MEDIUM
GHSA-w9qg-chfh-g3q9
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK
2 techniques across 2 tactics: Initial Access, Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS 4.8 (MEDIUM). Attack vector: Network. Complexity: Low. Privileges required: High. User interaction: Required. Exploitation requires authentication. Public exploit/POC available. |
| Exploit ScenarioDerived | An attacker (requires authentication) could exploit this vulnerability to compromise the affected system. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAIv1 – Mar 12, 2026
Stored XSS in Concrete CMS versions before 9.4.8 allows authenticated administrators to inject malicious scripts through the Switch Language block, affecting any site where a rogue admin account exists. Public exploit code is available for this vulnerability. A patch is available in version 9.4.8 and later.
Earlier versions of this analysis (1)
In Concrete CMS below version 9.4.8, a rogue administrator can add stored XSS via the Switch Language block. 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.
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.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 1 package in composer
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-79 (Cross-site Scripting (XSS)). Affects Concrete Cms. In Concrete CMS below version 9.4.8, a rogue administrator can add stored XSS via the Switch Language block. 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 M3dium for reporting.
Know when Concrete Cms gets its next vulnerability
- Watch products and get an email when something new is published
- Check this CVE against your own stack and servers
- Exploit and PoC references, threat intelligence from 22 sources
No credit card · 7-day full trial
Severity by source
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
Lifecycle Timeline
3DescriptionCVE.org
In Concrete CMS below version 9.4.8, a rogue administrator can add stored XSS via the Switch Language block. 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 M3dium for reporting.
Executive ViewAI
Organizations using Concrete CMS below should be aware of moderate risk from CVE-2026-3242, a cross-site scripting vulnerability rated CVSS 4.8. Attackers could inject scripts to steal sessions or perform actions as authenticated users. Proof-of-concept code is publicly available. A patch is available and should be applied during regular vulnerability management.
Apply vendor patch. If patching is delayed: implement CSP headers, enable HttpOnly cookies, deploy WAF XSS rules.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.
Affected Products (CPE)CVE.org
Related Vulnerabilities in Concrete CMS v9.4.8 Multiple Vulnerabilities
View all 6More in Concrete Cms
View allUnauthenticated user enumeration in Concrete CMS 9.0.0 through 9.5.2 allows any anonymous visitor to dump the complete b
A bypass of adding remote files in Concrete CMS (previously concrete5) File Manager leads to remote code execution in Co
Concrete5 through 8.5.5 deserializes Untrusted Data. Rated high severity (CVSS 7.2), this vulnerability is remotely expl
Concrete5 up to and including 8.5.2 allows Unrestricted Upload of File with Dangerous Type such as a .php file via File
Concrete5 before 8.5.3 allows Unrestricted Upload of File with Dangerous Type such as a .phar file. Rated high severity
A Server Side Request Forgery (SSRF) vulnerability in tools/files/importers/remote.php in concrete5 8.2.0 can lead to at
Unauthenticated file usage disclosure in Concrete CMS 9.5.0 and below exposes internal page structure to any network-acc
concrete5 8.1.0 places incorrect trust in the HTTP Host header during caching, if the administrator did not define a "ca
concrete5 8.1.0 has CSRF in Thumbnail Editor in the File Manager, which allows remote attackers to disable the entire in
Unauthenticated information disclosure in Concrete CMS 9.5.0 and earlier allows remote attackers to enumerate all conver
Unauthenticated information disclosure in Concrete CMS 9.5.0 and below allows any network-accessible attacker to enumera
Exploit-DB