{"id":"CVE-2026-81909","summary":"Concrete CMS 9 through 9.5.2 is vulnerable to Missing Authorization in the orphaned-block alias route, allowing an authenticated editor to disclose and force-delete arbitrary blocks","details":"Concrete CMS 9 through 9.5.2 is vulnerable to Missing Authorization in the block alias route (Process::alias() in concrete/controllers/backend/block/process.php).It does not verify that the referenced block is genuinely orphaned on the target page, nor that the caller holds any permission over the source block. A user granted only an area-scoped add_block_to_area delegation on their own page can therefore pass any block ID on the site: the source block's content is duplicated into an area the rogue editor controls, disclosing that content, and the original block is then force-deleted in the same request, destroying arbitrary site content. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.9 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.","modified":"2026-09-13T03:47:17.514659827Z","published":"2026-09-11T17:49:47.885Z","database_specific":{"cna_assigner":"ConcreteCMS","cwe_ids":["CWE-862"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81909.json"},"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-2026-81909.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-81909"},{"type":"PACKAGE","url":"https://github.com/concretecms/concretecms"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/concretecms/concretecms","events":[{"introduced":"b3774abddd475b4ba98b637402506f7a5ebd90ea"},{"last_affected":"8fe9708072c3815a5df719b592e4b23b43b4ff7a"}],"database_specific":{"extracted_events":[{"introduced":"9.0.0"},{"last_affected":"9.5.2"}],"source":"AFFECTED_FIELD"}}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-81909.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N"}]}