CVE-2021-4133

2021-12-1712:49:59

redhat.com

access.redhat.com

keycloak

security flaw

user accounts

rest api

mitigation

undertow

CVSS2

6.5

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

SINGLE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:L/Au:S/C:P/I:P/A:P

CVSS3

8.8

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

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

EPSS

0.005

Percentile

76.0%

JSON

A flaw was found in Keycloak version 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.

Mitigation

Access to the user-creation functionality in the REST endpoint can be deactivated using CLI commands in undertow.
run:

bin/jboss-cli.sh --connect
/subsystem=undertow/configuration=filter/expression-filter=keycloakPathOverrideUsersCreateEndpoint:add( \
expression="(regex('^/auth/admin/realms/(.*)/users$') and method(POST))-> response-code(400)" \
)
/subsystem=undertow/server=default-server/host=default-host/filter-ref=keycloakPathOverrideUsersCreateEndpoint:add()