Is CVE-2026-8433 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-8433 being exploited in the wild.

How severe is CVE-2026-8433?

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-2026-8433?

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-2026-8433 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-8433?

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-2026-8433: Concrete CMS CSRF in file rescan controller

Q: Is there a fix for CVE-2026-8433?

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-2026-8433 attacked?

It is attacked over the network, in a web application.

Q: Am I affected by CVE-2026-8433?

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-2026-8433 · Severity: medium · CVSS 4 · Published 2026-05-21

Concrete CMS is a popular open-source content management system used for building and managing websites. A security flaw in the file management component allows an attacker to trick a logged-in administrator into performing unintended file rescan operations. While this specific action has limited direct impact, it could be used to disrupt administrative workflows or potentially facilitate more complex attacks.

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

Quick answers

Is CVE-2026-8433 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-8433 being exploited in the wild.
How severe is CVE-2026-8433?: 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-2026-8433?: 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-2026-8433 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-8433?: 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/backend/file rescan()' component. The application fails to properly validate CSRF tokens or implement sufficient SameSite cookie attributes for requests to this endpoint. An attacker can exploit this by inducing an authenticated user to visit a malicious webpage, which then silently triggers a file rescan operation in the background. This vulnerability is addressed in version 9.5.1.

Affected products

Concrete CMS Concrete CMS 9.0.0RC1 to 9.5.0

Identifiers

CVE-2026-8433
GHSA-6fxm-r8p3-mx5c

Timeline

2026-05-21: disclosed: NVD publication date
2026-05-22: advisory: GitHub Advisory published
2026-06-24: patched: GitHub Advisory updated with patch information

References

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

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