# CVE-2026-7888: Concrete CMS PHP object injection in Workflow and Form components

Source: https://junglewise.ai/threats/cve-2026-7888-concrete-cms-php-object-injection-in-workflow-and-form-components  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-03. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

CVE-2026-7888 · Severity: high · CVSS 4 · Published 2026-06-03

Concrete CMS, a popular content management system, is vulnerable to a security flaw in how it handles certain data related to forms, workflows, and file sets. An attacker who has already gained high-level access to the system could use this flaw to execute unauthorized code or take full control of the server. This could lead to a total loss of data confidentiality and system availability.

Technologies: [Concrete CMS](https://junglewise.ai/threats/technologies/concrete-cms), [concrete5/concrete5 (Packagist)](https://junglewise.ai/threats/technologies/concrete5-concrete5). Vendors: [Concrete CMS](https://junglewise.ai/threats/vendors/concrete-cms), [Packagist](https://junglewise.ai/threats/vendors/packagist).

## Quick answers

**Is CVE-2026-7888 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-7888 being exploited in the wild.

**How severe is CVE-2026-7888?** High severity, with a CVSS score of 4, published 3 June 2026.

**Which products and versions are affected?** Concrete CMS < 9.5.2; concrete5/concrete5 (Packagist) < 9.5.2, ECOSYSTEM:introduced=0,fixed=9.5.2.

**Is there a fix for CVE-2026-7888?** Yes. concrete5/concrete5 (Packagist): upgrade to 9.5.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-7888 attacked?** It is attacked with local access, in a web application.

**Am I affected by CVE-2026-7888?** 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 9.5.2 or later

  ```sh
  composer require concrete5/concrete5:^9.5.2
  ```


## Technical details

Concrete CMS versions prior to 9.5.2 contain a PHP Object Injection vulnerability (CWE-502) due to the insecure use of the unserialize() function. The affected components—Workflow, Form block, and File/Set—fail to implement the 'allowed_classes' restriction, allowing for the instantiation of arbitrary PHP objects. While the attack vector is listed as local with high privileges required in CVSS metrics, the advisory notes that an unauthenticated attacker could trigger the injection if a malicious serialized payload is successfully placed in the database. Successful exploitation can lead to remote code execution depending on available gadget chains. The issue is resolved in version 9.5.2.

## Affected products

- Concrete CMS Concrete CMS < 9.5.2

## Identifiers

- CVE-2026-7888
- GHSA-52pr-7vmf-2w7x

## Timeline

- 2026-06-03: advisory: GitHub Advisory and NVD entry published
- 2026-06-03: patched: Version 9.5.2 released

## References

- [https://documentation.concretecms.org/9-x/developers/introduction/version-history/952-release-notes](https://documentation.concretecms.org/9-x/developers/introduction/version-history/952-release-notes)
- [https://github.com/concretecms/concretecms/releases/tag/9.5.2](https://github.com/concretecms/concretecms/releases/tag/9.5.2)

## Related threats

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