Cross-site Request Forgery (CSRF) Affecting concrete5/concrete5 package, versions <9.5.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PHP-CONCRETE5CONCRETE5-17660457
- published27 Jun 2026
- disclosed21 May 2026
- creditUnknown
Introduced: 21 May 2026
CVE-2026-8421 (opens in a new tab)How to fix?
Upgrade concrete5/concrete5 to version 9.5.1 or higher.
Overview
concrete5/concrete5 is a concrete5 open source CMS.
Affected versions of this package are vulnerable to Cross-site Request Forgery (CSRF) via the install_package function in concrete/controllers/single_page/dashboard/extend/install.php. An attacker can execute arbitrary code by tricking an authenticated administrator with package installation permissions into visiting a crafted page, provided a malicious package is present under the designated directory. This is only exploitable if the victim is authorized to install packages.