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.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2026-9803)

ID	Name	Product	Family	Type	Severity
459203	Echo: keycloak-25: security update to 25.0.6+e1org.keycloak:keycloak-services: security update to 26.6.3	Tenable Cloud Security	Echo Local Security Checks	Local	medium
459203	Echo: keycloak-25: security update to 25.0.6+e1org.keycloak:keycloak-services: security update to 26.6.3	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	medium
444278	SCA: security update for org.keycloak:keycloak-services (GHSA-cpf7-j4cf-vqx4)	Tenable Cloud Security	SCA Checks	Local	medium
444278	SCA: security update for org.keycloak:keycloak-services (GHSA-cpf7-j4cf-vqx4)	Tenable Self-Hosted Container Security	SCA Checks	Local	medium

Detections

Analytics

CVE-2026-9803

medium

Tenable Plugins

medium

medium

medium

medium