{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "5.0.0"
              },
              {
                "last_affected": "9.5.2"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "8fe9708072c3815a5df719b592e4b23b43b4ff7a"
            }
          ],
          "repo": "https://github.com/concretecms/concretecms",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "ConcreteCMS",
    "cwe_ids": [
      "CWE-352"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81920.json"
  },
  "details": "Concrete CMS below 9.5.3 was vulnerable to Cross-Site Request Forgery in the dashboard SEO Excluded Words page. The reset() controller action cleared the administrator-configured reserved-word list (concrete.seo.exclude_words) but did not validate the anti-CSRF token that the reset modal emitted, and it did not restrict the request to the POST method. A remote attacker who lured an authenticated user with SEO access to a crafted page could revert the reserved-word list to its default and silently alter future URL-slug generation for pages, files, topics, and other objects created through the Text urlify service, undoing the site's configured SEO slug policy. The Concrete CMS security team gave this vulnerability a CVSS v4.0 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 riodrwn for reporting.",
  "id": "CVE-2026-81920",
  "modified": "2026-09-18T03:31:03.514612011Z",
  "published": "2026-09-15T18:46:30.484Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81920.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-81920"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/concretecms/concretecms"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Concrete CMS below 9.5.3 is vulnerable to Cross-Site Request Forgery (CSRF) in Dashboard SEO Excluded Words Reset Endpoint"
}