CVE-2026-8347: Concrete CMS 9.5.0 and below is vulnerable to IDOR + wrong-authorization-level in Express association Reorder dialog
Concrete CMS 9.5.0 and below is vulnerable to IDOR + wrong-authorization-level in the Express association Reorder dialog. This can cause Cross-entity state tampering with view-only permission on one entry. To be affected, a website has to be using express and relying on express entity ordering. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Do not use the Concrete CMS Express association Reorder dialog / rely on Express entity ordering until an official fix is released. Restrict access to the reorder functionality to trusted administrator accounts via existing access controls.
- Operational
Audit sites for use of Concrete CMS Express and for reliance on Express entity ordering. Review and tighten permissions so that users with view-only access cannot access or invoke the reorder functionality; where Express ordering is not required, stop using or remove that usage.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-8347?
CVE-2026-8347 has a severity score of 20, indicating a critical vulnerability.
How do I fix CVE-2026-8347?
To fix CVE-2026-8347, update to Concrete CMS version 9.5.1 or later.
What vulnerabilities are associated with CVE-2026-8347?
CVE-2026-8347 is associated with IDOR and incorrect authorization levels in the Express association Reorder dialog.
Who is affected by CVE-2026-8347?
Websites using Concrete CMS 9.5.0 and below that utilize express entity ordering are at risk from CVE-2026-8347.
What could be the consequences of exploiting CVE-2026-8347?
Exploiting CVE-2026-8347 may lead to cross-entity state tampering with entries that have view-only permissions.