A flaw was found in Keycloak. An unauthenticated attacker can exploit this vulnerability by sending a specially crafted POST request with an excessively long scope parameter to the OpenID Connect (OIDC) token endpoint. This leads to high resource consumption and prolonged processing times, ultimately resulting in a Denial of Service (DoS) for the Keycloak server.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 5
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Redhat Build_Of_Keycloak
cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:text-only:*:*:*
|
— | — |
|
Redhat Build_Of_Keycloak
cpe:2.3:a:redhat:build_of_keycloak:26.2:*:*:*:text-only:*:*:*
|
— | — |
|
Redhat Build_Of_Keycloak
cpe:2.3:a:redhat:build_of_keycloak:26.2.15:*:*:*:text-only:*:*:*
|
— | — |
|
Redhat Build_Of_Keycloak
cpe:2.3:a:redhat:build_of_keycloak:26.4:*:*:*:text-only:*:*:*
|
— | — |
|
Redhat Build_Of_Keycloak
cpe:2.3:a:redhat:build_of_keycloak:26.4.11:*:*:*:text-only:*:*:*
|
— | — |
References 6
https://access.redhat.com/errata/RHSA-2026:6475
secalert@redhat.com
https://access.redhat.com/errata/RHSA-2026:6476
secalert@redhat.com
https://access.redhat.com/errata/RHSA-2026:6477
secalert@redhat.com
https://access.redhat.com/errata/RHSA-2026:6478
secalert@redhat.com
https://access.redhat.com/security/cve/CVE-2026-4634
secalert@redhat.com
https://bugzilla.redhat.com/show_bug.cgi?id=2450250
secalert@redhat.com