CVE-2026-9803
Description
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Mitigation details
Description keycloak: Keycloak: Denial of Service via malformed Authorization header Red Hat statement A Moderate denial of service flaw was found in Keycloak's client registration endpoints. An unauthenticated attacker can send a specially crafted request with a malformed 'Authorization: Bearer' header, causing an ArrayIndexOutOfBoundsException and an HTTP 500 error. This can lead to a temporary…
Description
keycloak: Keycloak: Denial of Service via malformed Authorization header
Red Hat statement
A Moderate denial of service flaw was found in Keycloak's client registration endpoints. An unauthenticated attacker can send a specially crafted request with a malformed 'Authorization: Bearer' header, causing an ArrayIndexOutOfBoundsException and an HTTP 500 error. This can lead to a temporary disruption of service for the Keycloak instance.
CVSS v3: 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
Package state
| Product | Package | State |
|---|---|---|
| Red Hat Build of Keycloak | rhbk/keycloak-rhel9 | Affected |
Affected
| Vendor | Product | Version |
|---|---|---|
| redhat | Red Hat Build of Keycloak | Affected |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| redhat | build_of_keycloak | - | |
References
CWEs
CWE-125
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.