Concrete CMS below 9.5.4 allows privilege escalation because adding users and assigning groups do not require additional identity verification

Versions reported by the vendor

Affected version ranges reported by the assigning authority (ConcreteCMS). Independent of NVD's CPE analysis and usually ahead of it.

• Concrete CMS Concrete CMS

  • 9.0.0 and later · up to and including 9.5.2affected · git

Other highest-scoring records for the same primary product.

• CVE-2026-10721Concrete CMS below 9.5.2 is vulnerable to PHP Object Injection via unserialize() calls in the in Permission, Cache, and Search components
  33Monitor
• CVE-2026-7888Concrete CMS below 9.5.3 is vulnerable to PHP Object Injection via unserialize() calls in the Workflow, Form block, and File/Set components that lack the allowe
  33Monitor
• CVE-2026-81898Concrete CMS below version 9.5.3 is vulnerable to Stored XSS via country-less Address attribute in Express association views
  30Monitor
• CVE-2026-18113Concrete CMS 9.0 to 9.5.2 is vulnerable to Stored XSS in the Top Navigation Bar Block via Dropdown Child Page Names
  30Monitor
• CVE-2026-81899Concrete CMS 9.0 to 9.5.2 is vulnerable to Stored XSS via group folder name on the Members > Groups dashboard
  29Monitor
• CVE-2026-18115In Concrete CMS 9.2.0 to 9.5.2, Missing Authorization in REST API Users update() and change_password Enables Account Takeover.
  29Monitor

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Root cause

A function added for development or support ships to production without authentication. It often relies on the assumption that it is “only reachable from the internal network.”

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1// Added for the support team2app.post("/maintenance/reset", resetDevice);

1if (config.maintenanceEnabled) {2  app.post(3    "/maintenance/reset",4    requireSession, requireRole("admin"), resetDevice5  );6}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.