CVE-2026-8421

HIGH EPSS 6.7%

Published May 21, 20261mo ago · Modified Jun 17, 20262w ago

7.5 CVSS 4.0

High

Published May 21, 2026 1mo ago

Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score

7.5

Exploitability

—

Impact

—

Vector string

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector Network

Attack Complexity High

Privileges Required None

User Interaction A

Scope X

Threat Intelligence

EPSS Exploit Probability

6.7% percentile

Exploit & Patch Status

No Known Exploit

No Patch Available

Weaknesses 1

CWE-352 Cross-Site Request Forgery (CSRF) Authentication

Affected Products 1

Vendor	Product	Version	Range
concretecms	concrete_cms	*	<9.5.1

References 1

documentation.concretecms.org https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes

Release Notes

Remediation

No remediation data recorded yet

Check vendor advisories and the NVD entry for patch availability.