Vulnerability Details CVE-2026-9803
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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 26.4%
CVSS Severity
CVSS v3 Score 5.3
References
Products affected by CVE-2026-9803
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cpe:2.3:a:redhat:build_of_keycloak:-