CVE-2026-8427

High

Description

Concrete CMS 9 before 9.5.0 is vulnerable to Cross Site Request Forgery (CSRF) at concrete/controllers/backend/file removeFavoriteFolder($id). 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:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori (Tenzai) for reporting.

SeverityHigh

CVSS8.8

Exploit probability—

Product

Concretecms Concrete Cms

PublishedMay 21, 2026

First seenMay 21, 2026

Weakness typeCWE-352Cross-site request forgery (CSRF)CWE-1275CWE-1275

How to fix

Update

concretecms concrete_cms9.5.1 or later
concrete5/concrete59.5.1 or later

Vendor advisories

documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes

Affected products

Product	Affected versions	Fixed in
concretecms concrete_cms	9.0.0 ≤ v < 9.5.1	9.5.1
concrete5/concrete5Packagist	9.0.0RC1 ≤ v < 9.5.1	9.5.1

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.