# CVE-2026-81924: Concrete CMS CSRF in theme page-template activation

Source: https://junglewise.ai/threats/cve-2026-81924-concrete-cms-csrf-in-theme-page-template-activation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-15. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-81924 · Severity: medium · CVSS 6.5 · Published 2026-09-15

Concrete CMS, a popular open-source website content management system, contains a cross-site request forgery (CSRF) vulnerability in its theme configuration interface. An attacker could trick a signed-in administrator into visiting a malicious webpage that automatically submits a forged request to modify the site's theme page-template settings without the administrator's knowledge or consent, allowing unauthorized changes to site configuration.

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

## Quick answers

**Is CVE-2026-81924 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-81924 being exploited in the wild.

**How severe is CVE-2026-81924?** Medium severity, with a CVSS score of 6.5, published 15 September 2026.

**Which products and versions are affected?** Concrete CMS before 9.5.3.

**Is there a fix for CVE-2026-81924?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-81924 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-81924?** Check whether you run Concrete CMS 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.

## Technical details

The vulnerability exists in the Dashboard theme Inspect controller's activate_files() action, which processes theme page-template activation requests. The action creates PageTemplate records from attacker-supplied pageTemplates[] parameter values without validating an anti-CSRF token, violating CSRF protection best practices. An attacker can exploit this by hosting a page with JavaScript that auto-submits a POST request to the vulnerable endpoint; when a signed-in administrator visits the attacker's page, the browser automatically includes the administrator's valid session cookies, causing the forged request to execute with administrative privileges. The vulnerability requires the victim to be an authenticated administrator and involves some user interaction (visiting a malicious page), but no patch information is provided in the advisory text.

## Affected products

- Concrete CMS Concrete CMS before 9.5.3

## Timeline

- 2026-09-15: disclosed

## References

- [https://github.com/concretecms/concretecms](https://github.com/concretecms/concretecms)
- [https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes](https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes)

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