CVE-2026-19418: Typo3/cms backend TYPO3 CMS - Broken Access Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-68jx-f42c-7599",
  "modified" : "2026-09-01T21:31:42Z",
  "published" : "2026-09-01T21:31:42Z",
  "aliases" : [ "CVE-2026-19418" ],
  "summary" : "TYPO3 CMS - Broken Access Control in Backend and Install Tool",
  "details" : "### Problem\nThe referrer enforcement introduced with [TYPO3-CORE-SA-2020-006](https://news.typo3.com/security/advisory/typo3-core-sa-2020-006) ([CVE-2020-11069](https://www.cve.org/CVERecord?id=CVE-2020-11069)) became ineffective in TYPO3 v13.0, where TYPO3 CMS started serving the backend and Admin Tool applications from the site's main entry script instead of the dedicated typo3/ directory.\n\nWhether a request originated from the backend or Install Tool itself was determined by comparing the referrer against the directory of the entry script, which since then is the site root. As a consequence, requests originating from any script running on one of the TYPO3 instance's own domains, such as a frontend page, were accepted by backend routes and Install Tool endpoints.\n\nAttackers able to execute JavaScript on one of those domains, for instance by exploiting a cross-site scripting vulnerability, could invoke these endpoints via Fetch/XHR with the privileges of an authenticated victim's user session.\n\n### Solution\nUpdate to TYPO3 versions 13.4.34 LTS, 14.3.6 LTS that fix the problem described.\n\n### Credits\nThanks to Hổ Cao Từ for reporting this issue, and to TYPO3 core & security team member Benjamin Franzke for fixing it.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms-backend"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "13.0.0"
      }, {
        "fixed" : "13.4.34"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "typo3/cms-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "14.0.0"
      }, {
        "fixed" : "14.3.6"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/TYPO3/typo3/security/advisories/GHSA-68jx-f42c-7599"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-19418"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/TYPO3/typo3/commit/4a75e862c589c85d795d7c65dcdc835f8f413efc"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/TYPO3/typo3/commit/a0e8ee06a40e959b9e7b06a4b1cb19d3a0d3dcf7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/TYPO3/typo3/commit/ae0abd329d52285fe6e92804c3608820ad45e872"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/typo3/cms-core/CVE-2026-19418.yaml"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/TYPO3/typo3"
  }, {
    "type" : "WEB",
    "url" : "https://news.typo3.com/security/advisory/typo3-core-sa-2026-021"
  }, {
    "type" : "WEB",
    "url" : "https://typo3.org/security/advisory/typo3-core-sa-2020-006"
  }, {
    "type" : "WEB",
    "url" : "https://typo3.org/security/advisory/typo3-core-sa-2026-021"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-346", "CWE-352" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-01T21:31:42Z",
    "nvd_published_at" : null
  }
}