CVE-2026-8421

Published: Mag 21, 2026 Last Modified: Mag 21, 2026
ExploitDB:
Other exploit source:
Google Dorks:
HIGH 7,5
Source: ff5b8ace-8b95-4078-9743-eac1ca5451de
Attack Vector: network
Attack Complexity: high
Privileges Required: none
User Interaction: active
Confidentiality: N/A
Integrity: N/A
Availability: N/A

Description

AI Translation Available

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.

352

Cross-Site Request Forgery (CSRF)

Stable
Abstraction: Compound Structure: Composite
Common Consequences
Security Scopes Affected:
Confidentiality Integrity Availability Non-Repudiation Access Control
Potential Impacts:
Gain Privileges Or Assume Identity Bypass Protection Mechanism Read Application Data Modify Application Data Dos: Crash, Exit, Or Restart
Applicable Platforms
Technologies: Web Based, Web Server
Likelihood of Exploit: Medium
View CWE Details
https://documentation.concretecms.org/9-x/developers/introd…
https://documentation.concretecms.org/9-x/developers/introduction/version-histo…