CVE-2021-4133
Description
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.
Statement
This flaw affects only Red Hat Single Sign-on 7.5.0. Red Hat Single Sign-on 7.4.x releases are NOT affected. Fix is available for download from customer portal which can be applied on RH-SSO 7.5.0
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()
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.3 | 8.8 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | Low | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Acknowledgements
Red Hat would like to thank Grzegorz Sobański (MLabs) for reporting this issue.
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