CVE-2026-81909

The record

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.

Affected packages

Related vulnerabilities

• CVE-2026-96391 Missing Authorization vulnerability in Drupal Webform REST allows Forceful Browsing. CWE-862
• CVE-2026-96380 Missing Authorization vulnerability in Drupal CSS Usage Analyzer allows Forceful Browsing. CWE-862
• CVE-2026-96386 Missing Authorization vulnerability in Drupal Smart Content allows Forceful Browsing. CWE-862
• CVE-2026-87955 Missing Authorization vulnerability in Drupal Ultimate Table Field allows Forceful… CWE-862
• CVE-2026-87954 Missing Authorization vulnerability in Drupal Taxonomy Term Glossary allows Forceful… CWE-862
• CVE-2026-87943 Missing Authorization vulnerability in Drupal SAML SSO - Service Provider allows Forceful… CWE-862
• CVE-2026-84916 Missing Authorization vulnerability in Drupal Islandora allows Forceful Browsing. CWE-862
• CVE-2026-84921 Missing Authorization vulnerability in Drupal Webform Submissions Delete allows Forceful… CWE-862