CVE-2021-3424: Keycloak services Keycloak Is Vulnerable To IDN Vulnerability

MODERATE
Advisory Identifier: GHSA-pf38-cw3p-22q9
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CVSS 5.3
CWE-287
Published
Advisory Summary

CVE-2021-3424 is a MODERATE (CVSS 5.3) keycloak is vulnerable to idn vulnerability (CWE-287: Improper Authentication) affecting Keycloak services libraries in the Maven ecosystem. The issue involves keycloak is vulnerable to idn homograph attack. Remediation is available by upgrading affected packages to version 18.0.0.

CVE-2021-3424 at a Glance

CVE Identifier CVE-2021-3424
GHSA Identifier GHSA-pf38-cw3p-22q9
Severity MODERATE
CVSS v3.1 Base Score 5.3
CWE Classification CWE-287: Improper Authentication
Affected Product Keycloak services
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.3

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

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

How to Fix CVE-2021-3424

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: 18.0.0 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-services</artifactId>
    <version>18.0.0</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-2021-3424, 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 18.0.0), 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-287: Improper Authentication, where when an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. 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 flaw was found in keycloak as shipped in Red Hat Single Sign-On 7.4 where IDN homograph attacks are possible. A malicious user can register himself with a name already registered and trick admin to grant him extra privileges.

CVE-2021-3424 Affected Keycloak services Versions

1 component(s)
Fixed Versions:
18.0.0
Product / Package Ecosystem Affected Versions Fixed Version
org.keycloak:keycloak-services
maven/org.keycloak/keycloak-services
Maven
< 18.0.0
18.0.0

References

NVD — CVE-2021-3424 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3424
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=1933320
Keycloak services Source Repository REPOSITORY
https://github.com/keycloak/keycloak

Frequently Asked Questions

What is CVE-2021-3424?
CVE-2021-3424 is a security vulnerability in Keycloak services involving Keycloak is vulnerable to IDN homograph attack under CWE-287: Improper Authentication.
Which Keycloak services versions are affected?
Affected versions include releases prior to 18.0.0 across affected packages: org.keycloak:keycloak-services.
What version fixes CVE-2021-3424?
Upgrading to 18.0.0 (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 18.0.0. Upgrade your dependency to 18.0.0 or later.
What is the CVSS score of CVE-2021-3424?
CVE-2021-3424 has a CVSS v3.1 base score of 5.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
What CWE is associated with CVE-2021-3424?
CVE-2021-3424 is classified under CWE-287: Improper Authentication (When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.).
How can I check Maven dependencies for CVE-2021-3424?
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-pf38-cw3p-22q9",
  "modified" : "2022-04-28T21:00:21Z",
  "published" : "2022-04-28T21:00:21Z",
  "aliases" : [ "CVE-2021-3424" ],
  "summary" : "Keycloak is vulnerable to IDN homograph attack",
  "details" : "A flaw was found in keycloak as shipped in Red Hat Single Sign-On 7.4 where IDN homograph attacks are possible. A malicious user can register himself with a name already registered and trick admin to grant him extra privileges.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-services"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "18.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-3424"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=1933320"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/keycloak/keycloak"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-287" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-04-28T21:00:21Z",
    "nvd_published_at" : "2021-06-01T19:15:00Z"
  }
}