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Medium

Keycloak has an Out-of-bounds Read

  • Disclosed: 28.05.2026
  • Updated: 11.10.2026 12:22

A flaw was found in Keycloak's ClientRegistrationAuth component. A remote unauthenticated attacker can exploit this vulnerability by sending a specially crafted POST request with a malformed 'Authorization: Bearer' header to any client registration endpoint. This can lead to an ArrayIndexOutOfBoundsException, causing the server to return an HTTP 500 error and resulting in a Denial of Service (DoS) for the affected service.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) org.keycloak:keycloak-services <= 26.4.7, >= 26.5.0, < 26.6.3 26.6.3

References

CVSS score 5.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness (CWE)
CWE-125
Platform
Java / Kotlin (Maven)
Package
org.keycloak:keycloak-services
Disclosed
28.05.2026
Updated
11.10.2026 12:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-cpf7-j4cf-vqx4 - CC BY 4.0

Vulnerability history: org.keycloak:keycloak-services

All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (98) in the archive
Total entries
98
First → latest
01.2022 08.2026
Without a fix
16
Exploited in attacks
0

Severity breakdown

  • Critical 3
  • High 26
  • Medium 51
  • Low 18

Disclosures per year

Severity:
  1. Keycloak: Unauthenticated account takeover via reset-credentials flow bypass
    Critical · 9.1 CVE-2026-18963 >= 26.0.0, < 26.4.15, >= 26.5.0, < 26.6.6, >= 26.7.0, < 26.7.2 26.4.15, 26.6.6, 26.7.2
  2. Keycloak: Unauthorized access via improper validation of encrypted SAML assertions
    High · 7.7 CVE-2026-2092 <= 26.2.5, >= 26.3.0, <= 26.4.7, >= 26.5.0 no fix
  3. Keycloak has privilege escalation via improper scope mapping enforcement
    High · 7.3 CVE-2026-9795 < 26.6.4 26.6.4
  4. Keycloak has an Out-of-bounds Read this entry
    Medium · 5.3 CVE-2026-9803 <= 26.4.7, >= 26.5.0, < 26.6.3 26.6.3
  5. Keycloak: Open redirect when using wildcard valid redirect URIs in Keycloak
    High · 8.1 CVE-2026-7504 < 26.6.2 26.6.2
  6. Keycloak: Session fixation in OIDC login flow that can lead to account takeover
    High · 7.5 CVE-2026-7507 < 26.6.2 26.6.2
  7. Keycloak: Access token disclosure and implicit flow bypass via forged client data
    High · 7.1 CVE-2026-7571 < 26.6.2 26.6.2
  8. Keycloak: Privilege escalation via forged authorization codes due to SingleUseObjectProvider isolation flaw
    High · 7.4 CVE-2026-4282 < 26.5.7 26.5.7
  9. Keycloak: Application-Level DoS via Scope Processing
    High · 7.5 CVE-2026-4634 < 26.5.7 26.5.7
  10. Keycloak: UMA Policy Resource Injection Allows Unauthorized Cross-User Permission Grants
    High · 8.1 CVE-2026-4636 < 26.5.7 26.5.7
  11. Keycloak: Redirect URI validation bypass via ..;/ path traversal in OIDC auth endpoint
    High · 7.3 CVE-2026-3872 < 26.5.7 26.5.7
  12. Keycloak: Unauthorized authentication via disabled SAML Identity Provider
    High · 8.1 CVE-2026-2603 < 26.5.5 26.5.5
  13. Keycloak allows authentication using an Identity Provider (IdP) even after it has been disabled by an administrator
    High · 8.1 CVE-2026-3009 < 26.5.5 26.5.5
  14. Keycloak fails to verify if an Identity Provider (IdP) is enabled before issuing tokens
    High · 8.8 CVE-2026-1486 >= 26.5.0, < 26.5.3, < 26.4.9 26.5.3, 26.4.9
  15. Keycloak affected by improper invitation token validation
    High · 8.1 CVE-2026-1529 >= 26.5.0, < 26.5.3, < 26.2.13, >= 26.3.0, < 26.4.9 26.5.3, 26.2.13, 26.4.9
  16. Keycloak hostname verification
    High · 8.2 CVE-2025-3501 < 26.2.2 26.2.2
  17. org.keycloak:keycloak-services has Inefficient Regular Expression Complexity
    High · 6.5 CVE-2024-10270 < 24.0.9, >= 25.0.0, < 26.0.6 24.0.9, 26.0.6
  18. Keycloak has session fixation in Elytron SAML adapters
    High · 7.1 CVE-2024-7341 < 22.0.12, >= 23.0.0, < 24.0.7, >= 25.0.0, < 25.0.5 22.0.12, 24.0.7, 25.0.5
  19. Keycloak's admin API allows low privilege users to use administrative functions
    High · 8.1 CVE-2024-3656 < 24.0.5 24.0.5
  20. Keycloak exposes sensitive information in Pushed Authorization Requests (PAR)
    High · 7.5 CVE-2024-4540 < 24.0.5 24.0.5
  21. Keycloak path traversal vulnerability in redirection validation
    High · 8.1 CVE-2024-1132 < 22.0.10, >= 23.0.0, < 24.0.3 22.0.10, 24.0.3
  22. Keycloak's unvalidated cross-origin messages in checkLoginIframe leads to DDoS
    High · 7.4 CVE-2024-1249 < 22.0.10, >= 23.0.0, < 24.0.3 22.0.10, 24.0.3
  23. Keycloak path traversal vulnerability in the redirect validation
    High · 7.1 CVE-2024-2419 < 22.0.10, >= 23.0.0, < 24.0.3 22.0.10, 24.0.3
  24. The redirect_uri validation logic allows for bypassing explicitly allowed hosts that would otherwise be restricted
    High · 7.1 CVE-2023-6291 < 23.0.3 23.0.3
  25. Keycloak vulnerable to Improper Client Certificate Validation for OAuth/OpenID clients
    High · 7.1 CVE-2023-2422 < 21.1.2 21.1.2
  26. Keycloak vulnerable to cross-site scripting when validating URI-schemes on SAML and OIDC
    Critical · 10.0 CVE-2022-4361 < 21.1.2 21.1.2
  27. Keycloak vulnerable to user impersonation via stolen UUID code
    High · 8.7 CVE-2023-0264 < 21.0.1 21.0.1
  28. JBoss Keycloak CSRF Vulnerability
    High · 8.8 CVE-2014-3709 < 1.0.3.Final 1.0.3.Final
  29. Keycloak vulnerable to privilege escalation on Token Exchange feature
    Critical · 9.8 CVE-2022-1245 < 18.0.0 18.0.0
  30. Improper Authorization in Keycloak
    High · 8.8 CVE-2021-4133 < 15.1.1 15.1.1

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