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.
History

Thu, 02 Apr 2026 14:15:00 +0000

Type Values Removed Values Added
CPEs cpe:/a:redhat:build_keycloak: cpe:/a:redhat:build_keycloak:26.4::el9
References

Thu, 02 Apr 2026 13:15:00 +0000

Type Values Removed Values Added
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.
Title Keycloak: keycloak: denial of service via excessive processing of openid connect scope parameters
First Time appeared Redhat
Redhat build Keycloak
Weaknesses CWE-1050
CPEs cpe:/a:redhat:build_keycloak:
Vendors & Products Redhat
Redhat build Keycloak
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-04-02T16:35:02.691Z

Reserved: 2026-03-23T08:41:40.650Z

Link: CVE-2026-4634

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-04-02T13:16:27.027

Modified: 2026-04-02T14:16:33.590

Link: CVE-2026-4634

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.