CVE-2021-20202: Keycloak core Temporary Directory Hijacking Vulnerability Vulnerability

HIGH
Advisory Identifier: GHSA-6xp6-fmc8-pmmr
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CVSS 7.3
CWE-377
Published
Advisory Summary

CVE-2021-20202 is a HIGH (CVSS 7.3) temporary directory hijacking vulnerability vulnerability (CWE-377: Insecure Temporary File) affecting Keycloak core libraries in the Maven ecosystem. The issue involves temporary directory hijacking vulnerability in keycloak. Remediation is available by upgrading affected packages to version 13.0.0.

CVE-2021-20202 at a Glance

CVE Identifier CVE-2021-20202
GHSA Identifier GHSA-6xp6-fmc8-pmmr
Severity HIGH
CVSS v3.1 Base Score 7.3
CWE Classification CWE-377: Insecure Temporary File
Affected Product Keycloak core
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 7.3

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

Attack Vector Local (AV:L)
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 Low (A:L)

How to Fix CVE-2021-20202

To remediate this vulnerability, upgrade all affected Keycloak core 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-core fixed: 13.0.0 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-core</artifactId>
    <version>13.0.0</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-2021-20202, 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 core in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 13.0.0), 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-377: Insecure Temporary File, where creating and using insecure temporary files can leave application and system data vulnerable to attack. In Keycloak core, 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. Directories can be created prior to the Java process creating them in the temporary directory, but with wider user permissions, allowing the attacker to have access to the contents that keycloak stores in this directory. The highest threat from this vulnerability is to data confidentiality and integrity.

CVE-2021-20202 Affected Keycloak core Versions

1 component(s)
Fixed Versions:
13.0.0
Product / Package Ecosystem Affected Versions Fixed Version
org.keycloak:keycloak-core
maven/org.keycloak/keycloak-core
Maven
< 13.0.0
13.0.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/JLLeitschuh/security-research/security/advisories/GHSA-7gf3-89f6-823j
NVD — CVE-2021-20202 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-20202
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=1922128
issues.redhat.com/browse/keycloak-170... WEB
https://issues.redhat.com/browse/KEYCLOAK-17000

Frequently Asked Questions

What is CVE-2021-20202?
CVE-2021-20202 is a security vulnerability in Keycloak core involving Temporary Directory Hijacking Vulnerability in Keycloak under CWE-377: Insecure Temporary File.
Which Keycloak core versions are affected?
Affected versions include releases prior to 13.0.0 across affected packages: org.keycloak:keycloak-core.
What version fixes CVE-2021-20202?
Upgrading to 13.0.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is keycloak-core affected?
Yes, org.keycloak:keycloak-core is affected in releases prior to 13.0.0. Upgrade your dependency to 13.0.0 or later.
What is the CVSS score of CVE-2021-20202?
CVE-2021-20202 has a CVSS v3.1 base score of 7.3 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L.
What CWE is associated with CVE-2021-20202?
CVE-2021-20202 is classified under CWE-377: Insecure Temporary File (Creating and using insecure temporary files can leave application and system data vulnerable to attack.).
How can I check Maven dependencies for CVE-2021-20202?
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-6xp6-fmc8-pmmr",
  "modified" : "2022-03-18T17:50:45Z",
  "published" : "2022-03-18T17:50:45Z",
  "aliases" : [ "CVE-2021-20202" ],
  "summary" : "Temporary Directory Hijacking Vulnerability in Keycloak",
  "details" : "A flaw was found in keycloak. Directories can be created prior to the Java process creating them in the temporary directory, but with wider user permissions, allowing the attacker to have access to the contents that keycloak stores in this directory. The highest threat from this vulnerability is to data confidentiality and integrity.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "13.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/JLLeitschuh/security-research/security/advisories/GHSA-7gf3-89f6-823j"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-20202"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=1922128"
  }, {
    "type" : "WEB",
    "url" : "https://issues.redhat.com/browse/KEYCLOAK-17000"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-377" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-17T21:01:15Z",
    "nvd_published_at" : "2021-05-12T15:15:00Z"
  }
}