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.

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

Q: 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.

Q: 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.

Q: How is CVE-2026-8428 attacked?

It is attacked over the network, in a network appliance.

Q: 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.

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, concrete5/concrete5 (Packagist). Vendors: Concrete CMS, 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
```
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

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