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GHSA-4c8m-6fwx-m7xq

Concrete CMS contains a CSRF vulnerability

Source: GitHub Advisory Database (reviewed) High CVE-2026-8421

Packages

EcosystemPackageAffectedFixed in
Packagist concrete5/concrete5 < 9.5.1 9.5.1

Details

As written in the advisory (Markdown source, shown as plain text).

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 thanks @maru1009 for reporting this issue.

References

External links from the advisory. They lead to third-party sites.