CVE-2026-4633: Keycloak services Keycloak's Identity-first Login Flow Exposes Vulnerability

LOW
Advisory Identifier: GHSA-rhgq-f8x5-j2jc
Share
CVSS 3.7
CWE-209
Published
Advisory Summary

CVE-2026-4633 is a LOW (CVSS 3.7) keycloak's identity-first login flow exposes vulnerability (CWE-209: Generation of Error Message Containing Sensitive Information) affecting Keycloak services libraries in the Maven ecosystem. The issue involves keycloak's identity-first login flow exposes user information. Remediation is available by upgrading affected packages to version 26.6.1, 26.4.12.

CVE-2026-4633 at a Glance

CVE Identifier CVE-2026-4633
GHSA Identifier GHSA-rhgq-f8x5-j2jc
Severity LOW
CVSS v3.1 Base Score 3.7
CWE Classification CWE-209: Generation of Error Message Containing Sensitive Information
Affected Product Keycloak services
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 3.7

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

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

How to Fix CVE-2026-4633

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: 26.6.1 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-services</artifactId>
    <version>26.6.1</version>
</dependency>
org.keycloak:keycloak-services fixed: 26.4.12 
<dependency>
    <groupId>org.keycloak</groupId>
    <artifactId>keycloak-services</artifactId>
    <version>26.4.12</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-2026-4633, 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 26.6.1), 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-209: Generation of Error Message Containing Sensitive Information, where the product generates an error message that includes sensitive information about its environment, users, or associated data. 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. A remote attacker can exploit differential error messages during the identity-first login flow when Organizations are enabled. This vulnerability allows an attacker to determine the existence of users, leading to information disclosure through user enumeration.

CVE-2026-4633 Affected Keycloak services Versions

2 component(s)
Fixed Versions:
26.6.126.4.12
Product / Package Ecosystem Affected Versions Fixed Version
org.keycloak:keycloak-services
maven/org.keycloak/keycloak-services
Maven
≥ 26.5.0
< 26.6.1
26.6.1
org.keycloak:keycloak-services
maven/org.keycloak/keycloak-services
Maven
< 26.4.12
26.4.12

References

NVD — CVE-2026-4633 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-4633
Keycloak services Source Repository REPOSITORY
https://github.com/keycloak/keycloak/issues/47619
Keycloak services Source Repository REPOSITORY
https://github.com/keycloak/keycloak/pull/47635
Security Fix Commit FIX COMMIT
https://github.com/keycloak/keycloak/commit/b137016cc6dcfd9f59b2aa2e6d73af8b0ebf7c6e
Security Fix Commit FIX COMMIT
https://github.com/keycloak/keycloak/commit/b4558a874fa79341404ae4d2d8f240f22bfed340
Keycloak services Security Information SECURITY
https://access.redhat.com/security/cve/CVE-2026-4633
bugzilla.redhat.com/show_bug.cgi WEB
https://bugzilla.redhat.com/show_bug.cgi?id=2450247
Keycloak services Source Repository REPOSITORY
https://github.com/keycloak/keycloak

Frequently Asked Questions

What is CVE-2026-4633?
CVE-2026-4633 is a security vulnerability in Keycloak services involving Keycloak's identity-first login flow exposes user information under CWE-209: Generation of Error Message Containing Sensitive Information.
Which Keycloak services versions are affected?
Affected versions include releases prior to 26.6.1, 26.4.12 across affected packages: org.keycloak:keycloak-services.
What version fixes CVE-2026-4633?
Upgrading to 26.6.1, 26.4.12 (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 26.6.1, 26.4.12. Upgrade your dependency to 26.6.1, 26.4.12 or later.
What is the CVSS score of CVE-2026-4633?
CVE-2026-4633 has a CVSS v3.1 base score of 3.7 (LOW) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.
What CWE is associated with CVE-2026-4633?
CVE-2026-4633 is classified under CWE-209: Generation of Error Message Containing Sensitive Information (The product generates an error message that includes sensitive information about its environment, users, or associated data.).
How can I check Maven dependencies for CVE-2026-4633?
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-rhgq-f8x5-j2jc",
  "modified" : "2026-06-17T20:43:08Z",
  "published" : "2026-03-23T12:30:30Z",
  "aliases" : [ "CVE-2026-4633" ],
  "summary" : "Keycloak's identity-first login flow exposes user information",
  "details" : "A flaw was found in Keycloak. A remote attacker can exploit differential error messages during the identity-first login flow when Organizations are enabled. This vulnerability allows an attacker to determine the existence of users, leading to information disclosure through user enumeration.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-services"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "26.5.0"
      }, {
        "fixed" : "26.6.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "org.keycloak:keycloak-services"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "26.4.12"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-4633"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/issues/47619"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/pull/47635"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/commit/b137016cc6dcfd9f59b2aa2e6d73af8b0ebf7c6e"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/keycloak/keycloak/commit/b4558a874fa79341404ae4d2d8f240f22bfed340"
  }, {
    "type" : "WEB",
    "url" : "https://access.redhat.com/security/cve/CVE-2026-4633"
  }, {
    "type" : "WEB",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2450247"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/keycloak/keycloak"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-209" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-26T19:28:56Z",
    "nvd_published_at" : "2026-03-23T11:16:25Z"
  }
}