Description
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.
CVSS breakdown
CVSS 3.1
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected products
- RedHat / build_of_keycloak
- RedHat / build_of_keycloak26.2 – 26.2
- RedHat / build_of_keycloak26.2.15 – 26.2.15
- RedHat / build_of_keycloak26.4 – 26.4
- RedHat / build_of_keycloak26.4.11 – 26.4.11
References
- VENDOR_ADVISORYhttps://access.redhat.com/errata/RHSA-2026:6475
- VENDOR_ADVISORYhttps://access.redhat.com/errata/RHSA-2026:6476
- VENDOR_ADVISORYhttps://access.redhat.com/errata/RHSA-2026:6477
- VENDOR_ADVISORYhttps://access.redhat.com/errata/RHSA-2026:6478
- VENDOR_ADVISORYhttps://access.redhat.com/security/cve/CVE-2026-4634
- MISChttps://bugzilla.redhat.com/show_bug.cgi?id=2450250
Updated 9m ago · 8 sources