CVE-2026-18120: Missing Authorization in legacy Express entries search endpoint allows disclosure of Express entry data
Concrete CMS before 9.5.3 exposed a legacy Express entry search endpoint that returned entry result JSON without invoking the canViewExpressEntries() permission check applied by the normal dashboard and CSV Export flow. An unauthenticated visitor who knew or discovered an Express entity identifier could enumerate that entity's entry search results, disclosing attribute values intended to be restricted to privileged users. For Express entities that do not support entry-specific permissions (i.e., supportsEntrySpecificPermissions() returns false), per-entry permission filtering is additionally disabled via EntryList::ignorePermissions(). The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Daniel Powell for reporting.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Concrete CMSto a version that resolves this vulnerability.Fixed in 9.5.3
Event History
Frequently Asked Questions
Which deployments are exposed?
Concrete CMS versions before 9.5.3 are affected where legacy Express entry search endpoints are available. Exposure concerns Express entities whose entry search results contain attribute values intended only for privileged users.
What does an attacker need to exploit this?
An attacker does not need to authenticate or interact with a user, but must know or discover an Express entity identifier. The CVSS vector also identifies attack complexity as high and attack requirements as present.
Are all Express entities filtered the same way?
No. For entities that do not support entry-specific permissions, where supportsEntrySpecificPermissions() returns false, the affected flow additionally disables per-entry filtering through EntryList::ignorePermissions().
What version addresses the issue?
Upgrade Concrete CMS to version 9.5.3 or later.