CVE-2026-8237Medium· 5.3▾ TwilightPoC availableConcrete CMS 9.5.0 and below is vulnerable to IDOR. The `/ccm/frontend/conversations/message_detail` endpoint returns the full content of any conversation message. An unauthenticated attacker can enumerate all conversation messages, incl…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 29.2 · likelihood 0.1 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Public exploit / PoC code seen in 2 sources. Availability, not in-the-wild use.
Exploit-prediction probability, daily snapshots since Jul 23.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
0.2%
0.2% → 0.6%
1 GitHub repo · Nuclei ×1
Concrete CMS 9.5.0 and below is vulnerable to IDOR. The /ccm/frontend/conversations/message_detail endpoint returns the full content of any conversation message. An unauthenticated attacker can enumerate all conversation messages, including messages from restricted pages, member-only areas, and the moderation queue. File attachments with download URLs are also exposed. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with Vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Eldudareeno for reporting.
concrete_cms < 9.5.1Upgrade past the affected range:
concrete_cms 9.5.1Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-18120Medium· 5.9Concrete 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
CVE-2026-87028Medium· 6.5Concrete CMS 9 through 9.5.3 did not confirm that a board InstanceItem submitted to the custom-slot preview endpoint belonged to the board instance the requesting user was authorized to edit, and did not enforce page-view permission befo…
CVE-2026-87031Low· 2.7n Concrete CMS 9.2.0 through 9.5.3, the REST API user creation endpoint (POST /ccm/api/1.0/users, the add() method of concrete/src/Api/Controller/Users.php) did not perform a permission check before creating an account
CVE-2026-18426Medium· 6.5Concrete CMS 9.0.0 through 9.5.2 did not enforce a block-level edit-permission check on the Express Form block's control-management actions, which relied solely on CSRF token validation
CVE-2026-18425Low· 2.7Concrete CMS 9 before 9.5.3 authorized the dashboard sitemap reorder action (Concrete\Controller\Backend\Dashboard\SitemapUpdate) using only the global access_sitemap task permission and did not check per-page edit permission before upda…
CVE-2026-18422Medium· 6.5Concrete CMS before 9.5.3 did not enforce a destination-side authorization check and did not validate a CSRF token in the multilingual page assignment backend action (Backend\Page\Multilingual::assign)