# CVE-2026-8428: Concrete CMS CSRF in dashboard update controller

Source: https://junglewise.ai/threats/cve-2026-8428-concrete-cms-csrf-in-dashboard-update-controller  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-21. Updated: 2026-06-24  
License: CC BY 4.0 with a link back

CVE-2026-8428 · Severity: high · CVSS 4 · Published 2026-05-21

Concrete CMS, a popular web content management system, is vulnerable to an issue where an attacker can trick an administrator into performing a core system update. By convincing a logged-in administrator to visit a malicious website, the attacker can trigger a background request that forces the CMS to update to a specific version. This could lead to unauthorized system changes or service disruption if the administrator has the necessary permissions and update files are present on the server.

Technologies: [Concrete CMS](https://junglewise.ai/threats/technologies/concrete-cms), [concrete5/concrete5 (Packagist)](https://junglewise.ai/threats/technologies/concrete5-concrete5). Vendors: [Concrete CMS](https://junglewise.ai/threats/vendors/concrete-cms), [Packagist](https://junglewise.ai/threats/vendors/packagist).

## Quick answers

**Is CVE-2026-8428 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-8428 being exploited in the wild.

**How severe is CVE-2026-8428?** High severity, with a CVSS score of 4, published 21 May 2026.

**Which products and versions are affected?** Concrete CMS <= 9.5.0, 9.5.0 and below; concrete5/concrete5 (Packagist) < 9.5.1, ECOSYSTEM:introduced=0,fixed=9.5.1.

**Is there a fix for CVE-2026-8428?** Yes. concrete5/concrete5 (Packagist): upgrade to 9.5.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-8428 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-8428?** Check whether you run Concrete CMS or concrete5/concrete5 (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- concrete5/concrete5 (Packagist): upgrade to 9.5.1 or later

  ```sh
  composer require concrete5/concrete5:^9.5.1
  ```


## Technical details

A Cross-Site Request Forgery (CSRF) vulnerability exists in Concrete CMS versions 9.5.0 and below. While the 'local_available_update.php' view generates a CSRF token, the 'do_update()' method in the 'Update' controller fails to validate this token. An attacker can exploit this by crafting a malicious web page that sends a cross-site POST request to the dashboard update endpoint. If a victim with 'canUpgrade()' permissions is authenticated and a valid update version exists in the 'DIR_CORE_UPDATES' directory, the attacker can force the CMS to update to a version string of their choosing. This issue is resolved in version 9.5.1.

## Affected products

- Concrete CMS Concrete CMS <= 9.5.0

## Identifiers

- CVE-2026-8428
- GHSA-prxr-vjgc-2cq9

## Timeline

- 2026-05-21: disclosed
- 2026-05-21: advisory
- 2026-06-24: patched: Advisory updated with patch details for version 9.5.1

## References

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

## Related threats

- [Concrete CMS OAuth REST API authorization bypass](https://junglewise.ai/threats/cve-2026-85387-concrete-cms-oauth-rest-api-authorization-bypass)
- [Concrete CMS unauthenticated Express entry search disclosure](https://junglewise.ai/threats/cve-2026-18120-concrete-cms-unauthenticated-express-entry-search-disclosure)
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- [Concrete CMS stored XSS via XML file upload in Form Block](https://junglewise.ai/threats/cve-2026-85386-concrete-cms-stored-xss-via-xml-file-upload-in-form-block)