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.
Metrics
Affected Vendors & Products
References
History
Wed, 03 Jun 2026 19:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat build Of Keycloak
|
|
| CPEs | cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:* | |
| Vendors & Products |
Redhat build Of Keycloak
|
Sat, 30 May 2026 23:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat keycloak
|
|
| Vendors & Products |
Redhat keycloak
|
Thu, 28 May 2026 13:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Thu, 28 May 2026 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
threat_severity
|
Thu, 28 May 2026 06:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Keycloak: keycloak: denial of service via malformed authorization header | |
| First Time appeared |
Redhat
Redhat build Keycloak |
|
| Weaknesses | CWE-125 | |
| CPEs | cpe:/a:redhat:build_keycloak: | |
| Vendors & Products |
Redhat
Redhat build Keycloak |
|
| References |
| |
| Metrics |
cvssV3_1
|
Status: PUBLISHED
Assigner: redhat
Published:
Updated: 2026-05-28T13:10:07.051Z
Reserved: 2026-05-28T04:02:28.881Z
Link: CVE-2026-9803
Updated: 2026-05-28T13:10:03.763Z
Status : Analyzed
Published: 2026-05-28T06:16:29.750
Modified: 2026-06-03T19:28:55.667
Link: CVE-2026-9803
OpenCVE Enrichment
Updated: 2026-05-30T21:19:23Z