Concrete CMS 9.5.0 and below is vulnerable to authorization Bypass in the Calendar Event Frontend Dialog which can allow cross-calendar data disclosure. A public calendar block can be used as a pivot point to access private calendar data.
{
"cwe_ids": [
"CWE-639"
],
"github_reviewed": true,
"github_reviewed_at": "2026-06-24T18:12:55Z",
"nvd_published_at": "2026-05-21T21:16:33Z",
"severity": "MODERATE"
}