Red Hat · Red Hat Build Of Keycloak · CVE-2026-9803
**Name of the Vulnerable Software and Affected Versions**
Keycloak (affected versions not specified)
**Description**
A flaw in the ClientRegistrationAuth component allows a remote unauthenticated attacker to cause a Denial of Service (DoS). By sending a specially crafted POST request with a malformed `Authorization: Bearer` header to any client registration endpoint, an ArrayIndexOutOfBoundsException is triggered. This results in the server returning an HTTP 500 error, making the affected service unavailable.
**Recommendations**
At the moment, there is no information about a newer version that contains a fix for this vulnerability.