Concrete CMS up to 9.5.2 Block Arrangement ArrangeBlocks.php arrange cross-site request forgery

Summaryinfo

A vulnerability, which was classified as problematic, was found in Concrete CMS up to 9.5.2. Affected by this issue is the function Concrete\Controller\Backend\Page\ArrangeBlocks::arrange of the file ArrangeBlocks.php of the component Block Arrangement. Such manipulation leads to cross-site request forgery. This vulnerability is traded as CVE-2026-81919. The attack may be launched remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Concrete CMS up to 9.5.2. It has been rated as problematic. Affected by this issue is the function Concrete\Controller\Backend\Page\ArrangeBlocks::arrange of the file ArrangeBlocks.php of the component Block Arrangement. The manipulation with an unknown input leads to a cross-site request forgery vulnerability. Using CWE to declare the problem leads to 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. Impacted is integrity. CVE summarizes:

Concrete CMS below 9.5.3 did not validate an anti-CSRF token on the block-arrangement backend endpoint (the arrange() action of Concrete\Controller\Backend\Page\ArrangeBlocks). The action enforced page-edit authorization but performed no token check, and its route accepted any HTTP method, so an attacker could induce a signed-in content editor into loading an attacker-controlled page that auto-submitted a cross-site request and reordered or moved blocks in the draft version of a page the victim was permitted to edit. The default null cookie SameSite configuration let the victim's session cookie accompany the forged request. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

The advisory is shared for download at documentation.concretecms.org. This vulnerability is handled as CVE-2026-81919 since 08/27/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for 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:ArrangeBlocks.php it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 9.5.3 eliminates this vulnerability.

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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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