Is CVE-2026-8427 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-8427 being exploited in the wild.

How severe is CVE-2026-8427?

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-2026-8427?

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-2026-8427 attacked?

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

Am I affected by CVE-2026-8427?

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-2026-8427: Concrete CMS CSRF in removeFavoriteFolder backend controller

Q: Is there a fix for CVE-2026-8427?

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-2026-8427 attacked?

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

Q: Am I affected by CVE-2026-8427?

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-2026-8427 · Severity: medium · CVSS 4 · Published 2026-05-21

Concrete CMS, a popular content management system, is vulnerable to a security flaw that could allow an attacker to trick an administrator into unintentionally removing a folder from their 'favorites' list. This occurs because the system fails to verify that the request was intentionally initiated by the user. While the impact is limited to organizational preferences within the file manager, it represents a lapse in security controls that could be exploited through malicious links or websites.

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

Quick answers

Is CVE-2026-8427 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-8427 being exploited in the wild.
How severe is CVE-2026-8427?: 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-2026-8427?: 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-2026-8427 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-8427?: 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. The 'removeFavoriteFolder' method in the backend file controller (concrete/controllers/backend/file) does not implement sufficient CSRF token validation. An attacker can exploit this by inducing an authenticated user to visit a malicious webpage or click a crafted link, leading to the unauthorized removal of favorite folders from the user's workspace. The vulnerability is addressed in version 9.5.1 by implementing proper request validation.

Affected products

Concrete CMS Concrete CMS 9.0.0RC1 to 9.5.0

Identifiers

CVE-2026-8427
GHSA-67hj-8239-cmf5

Timeline

2026-05-21: disclosed: NVD publication 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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