Concrete CMS up to 9.5.2 Boards Custom Slot Dialog Controller custom_slot.php saveTemplate cross-site request forgery

Summaryinfo

A vulnerability, which was classified as problematic, was found in Concrete CMS up to 9.5.2. This issue affects the function saveTemplate of the file concrete/controllers/dialog/board/custom_slot.php of the component Boards Custom Slot Dialog Controller. Executing a manipulation can lead to cross-site request forgery. This vulnerability appears as CVE-2026-84432. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability was found in Concrete CMS up to 9.5.2. It has been declared as problematic. This vulnerability affects the function saveTemplate of the file concrete/controllers/dialog/board/custom_slot.php of the component Boards Custom Slot Dialog Controller. The manipulation with an unknown input leads to a cross-site request forgery vulnerability. The CWE definition for the vulnerability is CWE-352. The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request. As an impact it is known to affect integrity. CVE summarizes:

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.

The advisory is shared for download at documentation.concretecms.org. This vulnerability was named CVE-2026-84432 since 09/01/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

By approaching the search of inurl:concrete/controllers/dialog/board/custom_slot.php it is possible to find vulnerable targets with Google Hacking.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Content Management System

Name

• Concrete CMS

Version

• 9.5.0
• 9.5.1
• 9.5.2

License

• open-source

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