cvedb.io
CVE-2026-8426
HIGH · CVSS 8.8
EPSS exploitation probability: 0%
Published 2026-05-21T21:16:34.243 · Last modified 2026-06-17T11:03:55.633

Summary

Concrete CMS 9.5.0 and below does not validate a CSRF token before processing requests to /dashboard/extend/update/prepare_remote_upgrade/<remoteMPID>. An attacker who controls the remote package returned for a known marketplace item ID can overwrite the package PHP on disk and force its upgrade() method to execute in a single browser navigation. This results in remote code execution as the web server user.   In order to be vulnerable, the victim must be passing canInstallPackages, victim site must be connected to the Concrete marketplace; and the attacker controls the package returned for a marketplace item ID already installed on the victim site. 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/S

Affected products

concretecms — concrete_cms

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.