Vulnerability · Published Sep 10, 2026 · Assigned by ConcreteCMS
CVE-2026-84432Concrete CMS 9 through 9.5.2 is vulnerable to CSRFin the Boards custom slot dialog controller
Medium 5.3
In plain English
A medium-severity cross-site request forgery in Concrete CMS from Concrete CMS. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).
Official description
Concrete CMS 9 through 9.5.2 did not validate an anti-CSRF token in the Boards custom slot dialog controller (concrete/controllers/dialog/board/custom_slot.php) saveTemplate() action. The action created a board_slot_proxy Block and dispatched an AddCustomSlotToBoardCommand against a board instance while gating only on the per-resource canEditBoardContents() permission, so a crafted cross-site request could cause a user holding board-edit permission with an active session to write attacker-chosen slot and template data to a board under their own authority. The state-changing database write completed before any downstream rendering, so the forged request succeeded even when the HTTP response returned a non-200 status. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.3 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Concrete CMS | Concrete CMS | 9.0.0 – through 9.5.2 |
Weakness: CWE-352 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N