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CVE-2026-8426

8.8 HIGH

Concrete CMS 9.5.0 and below does not validate a CSRF token before processing requests to /dashboard/extend/update/prepare_remote_upgrade...

Published: 2026-05-21 · Last updated: 2026-05-26

Severity and scoring

CVSS
8.8 HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE
CWE-352, CWE-829

Affected products

VendorProduct
concretecmsconcrete_cms

Description

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/SC:N/SI:N/SA:N. Thanks https://github.com/maru1009 for reporting.

Source: NVD

References

Related CVEs

Same vendor

  • CVE-2026-8340 — Concrete CMS 9.5.0 and below is vulnerable to CSRF via Backend\File::approveVersion (4.3 MEDIUM)
  • CVE-2026-8434 — Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file rescanMultiple() (8.8 HIGH)
  • CVE-2026-8433 — Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file rescan() (8.8 HIGH)
  • CVE-2026-8432 — Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file star() (8.8 HIGH)
  • CVE-2026-8427 — Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file removeFavoriteFolder(... (8.8 HIGH)

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