CVE-2021-4133: Red Hat Keycloak

High severity, CVSS 8.8. EPSS: 1.4% chance of exploitation in the next 30 days.

A flaw was found in Keycloak in versions from 12.0.0 and before 15.1.1 which allows an attacker with any existing user account to create new default user accounts via the administrative REST API even when new user registration is disabled.

Affected products

• Red Hat Keycloak: from 12.0.0, before 15.1.1 (fixed in 15.1.1)

Published 2022-01-25. Last modified 2026-06-17.