{"id":"CVE-2026-8428","aliases":["GHSA-prxr-vjgc-2cq9"],"url":"https://o3.security/vulnerability/CVE-2026-8428","summary":"CSRF token is not validated in the core CMS update controller for Concrete CMS 9.5.0 and below","details":"Concrete CMS 9.5.0 and below emits a CSRF token in the local_available_update.php view ($token->output('do_update')) but the corresponding do_update() method in concrete/controllers/single_page/dashboard/system/update/update.php never calls $this->token->validate('do_update'). The form is rendered as a POST form, meaning the token reaches the browser, but because the controller discards it without verification, an attacker can craft a cross-site POST that triggers a core CMS update to an attacker-specified version string.  In order to be vulnerable, theictim must be passing canUpgrade()anda valid update version must be present under DIR_CORE_UPDATES. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 7.5 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks https://github.com/maru1009 for reporting.","published":"2026-05-21T20:24:11.572Z","modified":"2026-08-12T03:51:30.741842361Z","cvss":null,"epss":{"score":0.00132,"percentile":0.03207,"asOf":"2026-08-18"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"concrete5/concrete5","fixedVersion":"9.5.1"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/8xxx/CVE-2026-8428.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-8428"},{"type":"PACKAGE","url":"https://github.com/concretecms/concretecms"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:30.741842361Z"}}