CVE-2026-18122: Concrete CMS 9.2.0 to 9.5.2 Express REST API list endpoint exposes restricted Express entries via Missing Authorization

Severity: medium (CVSS 6.0 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-11 · updated 2026-09-11
Weakness: CWE-862

Description

Concrete CMS 9.2.0 to 9.5.2 Express REST API list endpoint exposes restricted Express entries via Missing Authorization; the Concrete CMS REST API's Express entry collection endpoint disabled the per-entry view permission check. An OAuth token with read scope for an Express entity could enumerate entries that its user context lacked permission to view, disclosing each entry's public identifier, URL, label, dates, and any attribute or associated-entry data requested via the includes parameter. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 6.0 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks riodrwn for reporting.

References

https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes

Get alerted when CVE-2026-18122 or the next vulnerability affects your stack