CVE-2021-4133: Keycloak services Improper Authorization Vulnerability

HIGH
Advisory Identifier: GHSA-83x4-9cwr-5487
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CVSS 8.8
CWE-863
Published
Advisory Summary

CVE-2021-4133 is a HIGH (CVSS 8.8) improper authorization vulnerability (CWE-863: Incorrect Authorization) affecting Keycloak services libraries in the Maven ecosystem. The issue involves improper authorization in keycloak. Remediation is available by upgrading affected packages to version 15.1.1.

CVE-2021-4133 at a Glance

CVE Identifier CVE-2021-4133
GHSA Identifier GHSA-83x4-9cwr-5487
Severity HIGH
CVSS v3.1 Base Score 8.8
CWE Classification CWE-863: Incorrect Authorization
Affected Product Keycloak services
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 8.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2021-4133

To remediate this vulnerability, upgrade all affected Keycloak services dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

org.keycloak:keycloak-services fixed: 15.1.1 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-services</artifactId>
    <version>15.1.1</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=org.keycloak

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2021-4133, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=org.keycloak

Analyze the terminal output to locate any version of Keycloak services in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 15.1.1), your application is affected.

Note: The mvn dependency:tree -Dincludes=org.keycloak command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-863: Incorrect Authorization, where the product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. In Keycloak services, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

A incorrect authorization flaw was found in Keycloak 12.0.0, the flaw allows an attacker with any existing user account to create new default user accounts via the administrative REST API even where new user registration is disabled.

CVE-2021-4133 Affected Keycloak services Versions

1 component(s)
Fixed Versions:
15.1.1
Product / Package Ecosystem Affected Versions Fixed Version
org.keycloak:keycloak-services
maven/org.keycloak/keycloak-services
Maven
< 15.1.1
15.1.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/keycloak/keycloak/security/advisories/GHSA-83x4-9cwr-5487
NVD — CVE-2021-4133 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-4133
Keycloak services Source Repository REPOSITORY
https://github.com/keycloak/keycloak/issues/9247
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2033602
Keycloak services Source Repository REPOSITORY
https://github.com/keycloak/keycloak
Keycloak services Security Information SECURITY
https://www.oracle.com/security-alerts/cpuapr2022.html

Frequently Asked Questions

What is CVE-2021-4133?
CVE-2021-4133 is a security vulnerability in Keycloak services involving Improper Authorization in Keycloak under CWE-863: Incorrect Authorization.
Which Keycloak services versions are affected?
Affected versions include releases prior to 15.1.1 across affected packages: org.keycloak:keycloak-services.
What version fixes CVE-2021-4133?
Upgrading to 15.1.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is keycloak-services affected?
Yes, org.keycloak:keycloak-services is affected in releases prior to 15.1.1. Upgrade your dependency to 15.1.1 or later.
What is the CVSS score of CVE-2021-4133?
CVE-2021-4133 has a CVSS v3.1 base score of 8.8 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-4133?
CVE-2021-4133 is classified under CWE-863: Incorrect Authorization (The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.).
How can I check Maven dependencies for CVE-2021-4133?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=org.keycloak'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-83x4-9cwr-5487",
  "modified" : "2022-02-02T16:07:18Z",
  "published" : "2022-01-06T18:32:58Z",
  "aliases" : [ "CVE-2021-4133" ],
  "summary" : "Improper Authorization in Keycloak",
  "details" : "A incorrect authorization flaw was found in Keycloak 12.0.0, the flaw allows an attacker with any existing user account to create new default user accounts via the administrative REST API even where new user registration is disabled.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-services"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "15.1.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/security/advisories/GHSA-83x4-9cwr-5487"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-4133"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/issues/9247"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2033602"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/keycloak/keycloak"
  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpuapr2022.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-863" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-01-04T20:27:06Z",
    "nvd_published_at" : "2022-01-25T20:15:00Z"
  }
}