Detections
Analytics

CVE-2026-87031

low

Description

n 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. As a result, any valid OAuth token carrying the users:add scope, including a client_credentials token with no associated user context, could create active, validated user accounts, bypassing email verification and administrator approval. Under default registration settings the created accounts could then edit page content, providing a path to stored cross-site scripting and further compromise. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Winston Crooker for reporting.

References

https://documentation.concretecms.org/developers/introduction/version-history/954-release-notes

Details

Source: Mitre, NVD

Published: 2026-09-16

Updated: 2026-09-21

Risk Information

CVSS v2

Base Score: 3.3

Vector: CVSS2#AV:N/AC:L/Au:M/C:N/I:P/A:N

Severity: Low

CVSS v3

Base Score: 2.7

Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N

Severity: Low

CVSS v4

Base Score: 2.1

Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Severity: Low

EPSS

EPSS: 0.0032