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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.

PUBLISHED Reserved 2026-05-12 | Published 2026-05-21 | Updated 2026-05-22 | Assigner ConcreteCMS




HIGH: 7.5CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Problem types

CWE-352 Cross-Site request forgery (CSRF)

Product status

Default status
unaffected

5.0 (git)
affected

References

documentation.concretecms.org/...n-history/951-release-notes release-notes

cve.org (CVE-2026-8421)

nvd.nist.gov (CVE-2026-8421)

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