CVE-2026-87031
Missing authorization in the REST API user creation endpoint in Concrete CMS 9.2.0 through 9.5.3 allows arbitrary account creation
Using Concrete CMS by Concrete CMS?
Get instant alerts when new vulnerabilities affect Concrete CMS - before attackers find them.
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.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
Remediation
No guide yetNo remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.
References (1)
SSVC — Action Prioritization
SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.
CVSS
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- HIGH
- User Interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality
- NONE
- Integrity
- LOW
- Availability
- NONE
Quick Info
Get alerted
Stop reading CVE feeds looking for your own stack
Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.