5.3
Medium
CVE-2026-9803 A flaw was found in Keycloak's ClientRegistrationAuth component
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.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| Red Hat Build of Keycloak | Versions not published | |
| Red Hat build of Keycloak 26.6.3 | Versions not published | |
| Red Hat build of Keycloak 26.6 26.6 | earliest → < 26.6-6 | 26.6-6 |
| Red Hat build of Keycloak 26.6.4 | Versions not published | |
| Red Hat build of Keycloak 26.4 26.4 | earliest → < 26.4-19 | 26.4-19 |
| Red Hat build of Keycloak 26.4.13 | Versions not published |
Other CVEs of Red Hat Build of Keycloak
The 277 CVEs of Red Hat Build of Keycloak →
CVE-2026-120984
Keycloak-services: keycloak-services: manage-clients to arbitrary code execution through inline javascript policy import
9.1
Critical
CVE-2026-9797
Keycloak: keycloak: privilege escalation via client authentication manipulation by an authenticated administrator
6.5
Medium
CVE-2026-97848
Keycloak-services: keycloak-services: protocol mapper with jsontype=json bypasses token sanitization
6.5
Medium
CVE-2026-97367
Keycloak-services: keycloak-services: dcr azp and sid claim substitution allows account rest session takeover
6.4
Medium