CVE-2026-18110 Concrete CMS - Broken Access Control

Concrete CMS 9 (9.0.0 through 9.5.2) contains an information disclosure vulnerability caused by missing authorization checks on the user selector autocomplete endpoint, letting unauthenticated attackers enumerate backend user accounts, exploit requires no authentication.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
Proof of concept available
Authentication
Not required
EPSS
0.27% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Broken Access Control
Impact
Information Disclosure
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Published
15 September 2026
Updated
15 October 2026
Weakness
CWE-862

Vendor fix

Update to the latest version beyond 9.5.2 where the authorization check is implemented.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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