CVE-2026-8421 Details
Description
Concrete CMS 9.5.0 and below contains a CSRF vulnerability in the install_package() method of concrete/controllers/single_page/dashboard/extend/install.php. An attacker who can cause an authenticated administrator to visit a crafted page, and who has placed or caused a package to be present under DIR_PACKAGES/<handle>/, can force the installation of that package without any CSRF protection. Package installation executes the package controller's install() method as the web server user, enabling remote code execution. In order to be vulnerable, the victim must be passing canInstallPackages. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 7.5 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks https://github.com/maru1009 for reporting.
A Cross-Site Request Forgery (CSRF) vulnerability has been identified in Concrete CMS versions 9.5.0 and below. The issue resides in the 'install_package()' method of 'concrete/controllers/single_page/dashboard/extend/install.php'. An attacker can exploit this vulnerability by causing an authenticated administrator to visit a malicious page while a targeted package is placed under 'DIR_PACKAGES/<handle>/'. This exploitation can lead to unauthorized package installation, executed as the web server user, thereby enabling remote code execution. The vulnerability is present when the victim has the 'canInstallPackages' permission.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed May 22, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes | ConcreteCMS | Release Notes |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-352 | Cross-Site Request Forgery (CSRF) | ConcreteCMS |
Affected Products
| Product | Versions |
|---|---|
| concretecms concrete cms | < 9.5.1 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 23, 2026 | CVE Translated | [email protected] |
| Jun 17, 2026 | CVE Modified | ConcreteCMS |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| May 26, 2026 | Initial Analysis | [email protected] |
| May 21, 2026 | New CVE Received | ConcreteCMS |