{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "5.0"
              },
              {
                "last_affected": "9.5.0"
              },
              {
                "introduced": "0"
              },
              {
                "fixed": "9.5.1"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "CPE_RANGE"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "92bae566b9ec573cfb3017fcbb6db454a6586997"
            }
          ],
          "repo": "https://github.com/concretecms/concretecms",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "ConcreteCMS",
    "cwe_ids": [
      "CWE-352",
      "CWE-829"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/8xxx/CVE-2026-8428.json"
  },
  "details": "Concrete CMS 9.5.0 and below emits a CSRF token in the local_available_update.php view ($token-\u003eoutput('do_update')) but the corresponding do_update() method in concrete/controllers/single_page/dashboard/system/update/update.php never calls $this-\u003etoken-\u003evalidate('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.",
  "id": "CVE-2026-8428",
  "modified": "2026-07-25T03:56:22.479927152Z",
  "published": "2026-05-21T20:24:11.572Z",
  "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"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "CSRF token is not validated in the core CMS update controller for Concrete CMS 9.5.0 and below"
}