CVE-2026-4634 HIGH

CVE-2026-4634: Keycloak: keycloak: denial of service via excessive processing of openid connect scope parameters

Vendor Red Hat
Product Red Hat build of Keycloak 26.2.15
Weakness CWE-1050
Published April 2, 2026
Last update June 30, 2026
View on NVD All CVEs

CVSS base score

7.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

April 2, 2026 CVE published
June 30, 2026 Record updated