CSRF token is not validated in the core CMS update controller for Concrete CMS 9.5.0 and below_CVE-2026-8428

{
    "lastseen": "",
    "description": "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.\u00a0\u00a0In order to be vulnerable, theictim must be passing canUpgrade()anda valid update version must be present under DIR_CORE_UPDATES.\u00a0The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of\u00a07.5 with vector\u00a0CVSS: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\u00a0https://github.com/maru1009\u00a0for reporting.",
    "published": "2026-05-21T20:24:11.572Z",
    "modified": "2026-05-21T20:24:11.572Z",
    "type": "cve",
    "title": "CSRF token is not validated in the core CMS update controller for Concrete CMS 9.5.0 and below",
    "source": "ConcreteCMS",
    "references": "https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes",
    "id": "CVE-2026-8428",
    "bulletinFamily": "",
    "cwe": [
        "CWE-352",
        "CWE-829"
    ],
    "cvelist": null,
    "sourceData": "Concrete CMS Concrete CMS 5.0",
    "sourceHref": "",
    "cvss": {
        "score": 7.5,
        "severity": "HIGH",
        "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",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "Concrete CMS",
    "version": "5.0",
    "vendor": "Concrete CMS",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}