Is CVE-2026-8435 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-8435 being exploited in the wild.

How severe is CVE-2026-8435?

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

Which products and versions are affected?

Concrete CMS >= 9.0.0RC1, = 9.0.0RC1, < 9.5.1, ECOSYSTEM:introduced=9.0.0RC1,fixed=9.5.1.

Is there a fix for CVE-2026-8435?

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-2026-8435 attacked?

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

Am I affected by CVE-2026-8435?

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-2026-8435: Concrete CMS CSRF in file version approval

Q: Is there a fix for CVE-2026-8435?

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-2026-8435 attacked?

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

Q: Am I affected by CVE-2026-8435?

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-2026-8435 · Severity: medium · CVSS 4 · Published 2026-05-21

Concrete CMS, a content management system used for building websites, is vulnerable to a security flaw that could allow an attacker to trick an administrator into performing unintended actions. Specifically, an attacker could cause a user with the appropriate permissions to approve a file version without their knowledge. This requires the attacker to successfully lure a logged-in administrator to a malicious website or link.

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

Quick answers

Is CVE-2026-8435 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-8435 being exploited in the wild.
How severe is CVE-2026-8435?: Medium severity, with a CVSS score of 4, published 21 May 2026.
Which products and versions are affected?: Concrete CMS >= 9.0.0RC1, < 9.5.1; concrete5/concrete5 (Packagist) >= 9.0.0RC1, < 9.5.1, ECOSYSTEM:introduced=9.0.0RC1,fixed=9.5.1.
Is there a fix for CVE-2026-8435?: 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-2026-8435 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-8435?: 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 flaw is located in the `approveVersion()` method within the `concrete/controllers/backend/file` controller. The application fails to properly validate CSRF tokens or implement sufficient SameSite cookie attributes for this specific endpoint. An attacker can exploit this by crafting a malicious webpage that, when visited by an authenticated administrator, triggers a background request to approve a specific file version. This could be used to bypass content review workflows. The issue is resolved in version 9.5.1.

Affected products

Concrete CMS Concrete CMS >= 9.0.0RC1, < 9.5.1

Identifiers

CVE-2026-8435
GHSA-44q4-354f-c826

Timeline

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

References

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

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