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Medium

Keycloak: Denial of Service due to excessive SAMLRequest decompression

  • Disclosed: 18.03.2026
  • Updated: 11.10.2026 13:20

A flaw was found in Keycloak. An unauthenticated remote attacker can trigger an application level Denial of Service (DoS) by sending a highly compressed SAMLRequest through the SAML Redirect Binding. The server fails to enforce size limits during DEFLATE decompression, leading to an OutOfMemoryError (OOM) and subsequent process termination. This vulnerability allows an attacker to disrupt the availability of the service.

Affected software

Click a technology to see all vulnerabilities affecting it.

PlatformPackageVulnerable versionsFixed in
Java / Kotlin (Maven) org.keycloak:keycloak-saml-adapter-core < 26.5.4 26.5.4
Java / Kotlin (Maven) org.keycloak:keycloak-saml-core < 26.5.4 26.5.4
Java / Kotlin (Maven) org.keycloak:keycloak-services < 26.5.4 26.5.4

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-409
Platform
Java / Kotlin (Maven)
Package
org.keycloak:keycloak-saml-adapter-core, org.keycloak:keycloak-saml-core, org.keycloak:keycloak-services
Disclosed
18.03.2026
Updated
11.10.2026 13:20

Sources and licenses

OSV / GitHub Advisory Database - GHSA-xv6h-r36f-3gp5 - 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: Open redirect when using wildcard valid redirect URIs in Keycloak
    High · 8.1 CVE-2026-7504 < 26.6.2 26.6.2
  5. 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
  6. Keycloak: Access token disclosure and implicit flow bypass via forged client data
    High · 7.1 CVE-2026-7571 < 26.6.2 26.6.2
  7. Keycloak: Privilege escalation via forged authorization codes due to SingleUseObjectProvider isolation flaw
    High · 7.4 CVE-2026-4282 < 26.5.7 26.5.7
  8. Keycloak: Application-Level DoS via Scope Processing
    High · 7.5 CVE-2026-4634 < 26.5.7 26.5.7
  9. Keycloak: UMA Policy Resource Injection Allows Unauthorized Cross-User Permission Grants
    High · 8.1 CVE-2026-4636 < 26.5.7 26.5.7
  10. Keycloak: Redirect URI validation bypass via ..;/ path traversal in OIDC auth endpoint
    High · 7.3 CVE-2026-3872 < 26.5.7 26.5.7
  11. Keycloak: Denial of Service due to excessive SAMLRequest decompression this entry
    Medium · 5.3 CVE-2026-2575 < 26.5.4 26.5.4
  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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