CVE-2021-4133

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-01-25 · updated 2026-06-17
Weakness: CWE-863

Description

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

Keycloak: from 12.0.0 before 15.1.1 — fixed in 15.1.1

How to fix

Upgrade to a fixed version: Keycloak 15.1.1. Check the vendor advisory for mitigations.

References

https://bugzilla.redhat.com/show_bug.cgi?id=2033602
https://github.com/keycloak/keycloak/issues/9247
https://github.com/keycloak/keycloak/security/advisories/GHSA-83x4-9cwr-5487
https://www.oracle.com/security-alerts/cpuapr2022.html
https://bugzilla.redhat.com/show_bug.cgi?id=2033602
https://github.com/keycloak/keycloak/issues/9247
https://github.com/keycloak/keycloak/security/advisories/GHSA-83x4-9cwr-5487
https://www.oracle.com/security-alerts/cpuapr2022.html

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