Is CVE-2026-8413 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-8413 being exploited in the wild.

How severe is CVE-2026-8413?

Medium severity, with a CVSS score of 4, published 21 May 2026.

Which products and versions are affected?

Concrete CMS 9.0.0RC1 to 9.5.0; concrete5/concrete5 (Packagist) >= 9.0.0RC1, < 9.5.1, ECOSYSTEM:introduced=9.0.0RC1,fixed=9.5.1.

Is there a fix for CVE-2026-8413?

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-2026-8413 attacked?

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

Am I affected by CVE-2026-8413?

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-2026-8413: Concrete CMS CSRF in bulk page design controller

Q: Is there a fix for CVE-2026-8413?

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-2026-8413 attacked?

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

Q: Am I affected by CVE-2026-8413?

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-2026-8413 · Severity: medium · CVSS 4 · Published 2026-05-21

Concrete CMS, a popular content management system, is vulnerable to a security flaw in its bulk page design tool. This vulnerability could allow an attacker to trick an authorized administrator into performing unintended design changes on multiple pages without their consent. While the impact is limited to unauthorized modifications of page layouts or styles, it could be used to deface parts of a website if a logged-in user visits a malicious link.

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

Quick answers

Is CVE-2026-8413 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-8413 being exploited in the wild.
How severe is CVE-2026-8413?: Medium severity, with a CVSS score of 4, published 21 May 2026.
Which products and versions are affected?: Concrete CMS 9.0.0RC1 to 9.5.0; concrete5/concrete5 (Packagist) >= 9.0.0RC1, < 9.5.1, ECOSYSTEM:introduced=9.0.0RC1,fixed=9.5.1.
Is there a fix for CVE-2026-8413?: 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-2026-8413 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-8413?: 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 9.0.0RC1 through 9.5.0 within the 'concrete/controllers/dialog/page/bulk/design' component. The application fails to properly validate CSRF tokens or implement sufficient SameSite cookie attributes (CWE-1275) for requests to this endpoint. An unauthenticated remote attacker can exploit this by inducing a logged-in administrator to visit a malicious webpage or click a crafted link. Successful exploitation allows the attacker to perform bulk design changes to pages on behalf of the victim. The issue is resolved in version 9.5.1.

Affected products

Concrete CMS Concrete CMS 9.0.0RC1 to 9.5.0

Identifiers

CVE-2026-8413
GHSA-mpq2-mv8p-9wm6

Timeline

2026-05-21: disclosed: NVD Published Date
2026-05-22: advisory: GitHub Advisory published
2026-06-24: patched: Advisory updated with patch information for version 9.5.1

References

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

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