CVE-2020-35509: Keycloak core Improper Certificate Validation Vulnerability

MODERATE
Advisory Identifier: GHSA-rpj2-w6fr-79hc
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CVSS 5.4
CWE-295 CWE-20
Published
Advisory Summary

CVE-2020-35509 is a MODERATE (CVSS 5.4) improper certificate validation vulnerability (CWE-295: Improper Certificate Validation) affecting Keycloak core libraries in the Maven ecosystem. The issue involves keycloak vulnerable to improper certificate validation. Remediation is available by upgrading affected packages to version 14.0.0.

CVE-2020-35509 at a Glance

CVE Identifier CVE-2020-35509
GHSA Identifier GHSA-rpj2-w6fr-79hc
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-295: Improper Certificate Validation
Affected Product Keycloak core
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 5.4

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:L/I:L/A:N).

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 Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2020-35509

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: 14.0.0 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-core</artifactId>
    <version>14.0.0</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-2020-35509, 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 14.0.0), 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-295: Improper Certificate Validation, where the product does not validate, or incorrectly validates, a certificate. 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

keycloak accepts an expired certificate by the direct-grant authenticator because of missing time stamp validations. The highest threat from this vulnerability is to data confidentiality and integrity. This issue was partially fixed in version [13.0.1](https://github.com/keycloak/keycloak/pull/6330) and more completely fixed in version [14.0.0](https://github.com/keycloak/keycloak/pull/8067).

CVE-2020-35509 Affected Keycloak core Versions

1 component(s)
Fixed Versions:
14.0.0
Product / Package Ecosystem Affected Versions Fixed Version
org.keycloak:keycloak-core
maven/org.keycloak/keycloak-core
Maven
< 14.0.0
14.0.0

References

NVD — CVE-2020-35509 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-35509
Keycloak core Source Repository REPOSITORY
https://github.com/keycloak/keycloak/pull/6330
Keycloak core Source Repository REPOSITORY
https://github.com/keycloak/keycloak/pull/8067
Security Fix Commit FIX COMMIT
https://github.com/keycloak/keycloak/commit/478319348bdfdb9b6d39122f41edf2af79f679bb
Keycloak core Security Information SECURITY
https://access.redhat.com/security/cve/cve-2020-35509
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=1912427
Keycloak core Source Repository REPOSITORY
https://github.com/keycloak/keycloak
Keycloak core Source Repository REPOSITORY
https://github.com/keycloak/keycloak/blob/4f330f4a57cbfcf6202b60546518261c66e59a35/services/src/main/java/org/keycloak/authentication/authenticators/x509/ValidateX509CertificateUsername.java#L74-L76

Frequently Asked Questions

What is CVE-2020-35509?
CVE-2020-35509 is a security vulnerability in Keycloak core involving Keycloak vulnerable to Improper Certificate Validation under CWE-295: Improper Certificate Validation.
Which Keycloak core versions are affected?
Affected versions include releases prior to 14.0.0 across affected packages: org.keycloak:keycloak-core.
What version fixes CVE-2020-35509?
Upgrading to 14.0.0 (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 14.0.0. Upgrade your dependency to 14.0.0 or later.
What is the CVSS score of CVE-2020-35509?
CVE-2020-35509 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.
What CWE is associated with CVE-2020-35509?
CVE-2020-35509 is classified under CWE-295: Improper Certificate Validation (The product does not validate, or incorrectly validates, a certificate.).
How can I check Maven dependencies for CVE-2020-35509?
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-rpj2-w6fr-79hc",
  "modified" : "2025-06-30T21:46:07Z",
  "published" : "2022-08-24T00:00:29Z",
  "aliases" : [ "CVE-2020-35509" ],
  "summary" : "Keycloak vulnerable to Improper Certificate Validation",
  "details" : "keycloak accepts an expired certificate by the direct-grant authenticator because of missing time stamp validations. The highest threat from this vulnerability is to data confidentiality and integrity.\n\nThis issue was partially fixed in version [13.0.1](https://github.com/keycloak/keycloak/pull/6330) and more completely fixed in version [14.0.0](https://github.com/keycloak/keycloak/pull/8067).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-core"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "14.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-35509"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/pull/6330"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/pull/8067"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/commit/478319348bdfdb9b6d39122f41edf2af79f679bb"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/cve-2020-35509"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=1912427"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/keycloak/keycloak"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/blob/4f330f4a57cbfcf6202b60546518261c66e59a35/services/src/main/java/org/keycloak/authentication/authenticators/x509/ValidateX509CertificateUsername.java#L74-L76"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20", "CWE-295" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-12-05T23:03:56Z",
    "nvd_published_at" : "2022-08-23T16:15:00Z"
  }
}