# CVE-2026-8240: Concrete CMS unauthenticated page metadata disclosure in summary templates

Source: https://junglewise.ai/threats/cve-2026-8240-concrete-cms-unauthenticated-page-metadata-disclosure-in-summary  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-21. Updated: 2026-06-24  
License: CC BY 4.0 with a link back

CVE-2026-8240 · Severity: medium · CVSS 4 · Published 2026-05-21

Concrete CMS, a platform used for building and managing websites, is affected by a security flaw that allows unauthorized users to see information about hidden pages. An attacker can discover the existence of private drafts and restricted pages, along with their titles, web addresses, and author names. This could lead to the exposure of sensitive internal information or upcoming content before it is officially published.

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-2026-8240 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-8240 being exploited in the wild.

**How severe is CVE-2026-8240?** Medium severity, with a CVSS score of 4, published 21 May 2026.

**Which products and versions are affected?** Concrete CMS <= 9.5.0, 9.5.0 and below; concrete5/concrete5 (Packagist) < 9.5.1, ECOSYSTEM:introduced=0,fixed=9.5.1.

**Is there a fix for CVE-2026-8240?** 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-2026-8240 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-8240?** 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

  ```sh
  composer require concrete5/concrete5:^9.5.1
  ```


## Technical details

Concrete CMS 9.5.0 and below contains an improper access control vulnerability (CWE-284) within its summary template functionality. When a summary template is configured, the system fails to properly validate permissions before rendering metadata, allowing unauthenticated remote attackers to disclose the existence of private, draft, and restricted pages. Leaked information includes page titles, paths, descriptions, and author metadata. The vulnerability is addressed in version 9.5.1 by implementing stricter permission checks (canViewRenderedSummaryTemplates) within the summary template drivers.

## Affected products

- Concrete CMS Concrete CMS <= 9.5.0

## Identifiers

- CVE-2026-8240
- GHSA-vpgr-cwfx-pwfw

## Timeline

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

## References

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

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