Quick answers
- Is CVE-2026-8337 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-8337 being exploited in the wild.
- How severe is CVE-2026-8337?
- 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-2026-8337?
- 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-2026-8337 attacked?
- It is attacked over the network, in a network appliance.
- Am I affected by CVE-2026-8337?
- 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
An Insecure Direct Object Reference (IDOR) vulnerability exists in Concrete CMS versions 9.5.0 and below within the survey functionality. The root cause is a lack of proper authorization checks on the survey voting endpoint. If a site hosts both public and private surveys, an unauthenticated attacker can discover the 'optionID' for a restricted survey and submit it through the public survey's endpoint. This allows the attacker to bypass access controls and register votes in surveys intended to be private. The vulnerability is addressed in version 9.5.1.
Affected products
- Concrete CMS Concrete CMS <= 9.5.0
Identifiers
- CVE-2026-8337
- GHSA-8c7c-h7px-267g
Timeline
- 2026-05-21: disclosed: NVD Published Date
- 2026-05-22: advisory: GitHub Advisory published
- 2026-06-24: patched: Advisory updated with patch information for version 9.5.1