Concrete CMS up to 9.5.2 Orphaned Block Removal removeOrphanedBlocks cross-site request forgery

Summaryinfo

A vulnerability was found in Concrete CMS up to 9.5.2. It has been classified as problematic. The impacted element is the function removeOrphanedBlocks of the component Orphaned Block Removal. The manipulation leads to cross-site request forgery. This vulnerability is documented as CVE-2026-81902. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Concrete CMS up to 9.5.2. This issue affects the function removeOrphanedBlocks of the component Orphaned Block Removal. 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. The summary by CVE is:

Concrete CMS 9 through 9.5.2 did not validate a CSRF token in the orphaned block removal panel action (removeOrphanedBlocks). A remote attacker could craft a request that, when loaded by an authenticated user holding edit permission on the target page, deleted every block on that page's current version; blocks not aliased to another page or scrapbook entry were also removed from the global Blocks table and their block-type data table, permanently destroying the content. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.1 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

It is possible to read the advisory at documentation.concretecms.org. The identification of this vulnerability is CVE-2026-81902 since 08/27/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit.

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

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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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