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HIGHCVE-2026-4634Published Modified CNA redhat

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

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.

Metrics

CVSS v3.1
7.5
Severity
HIGH
Fixed in
26.2.15-1
Affected Products
8

Fix available

26.2.15-126.2-1826.4.11-126.4-14
Affected packages
  • Red Hat / Red Hat build of Keycloak 26.2
    Fixed in 26.2.15-1
  • Red Hat / Red Hat build of Keycloak 26.2
    Fixed in 26.2-18
  • Red Hat / Red Hat build of Keycloak 26.2
    Fixed in 26.2-18
  • Red Hat / Red Hat build of Keycloak 26.2.15
  • Red Hat / Red Hat build of Keycloak 26.4
    Fixed in 26.4.11-1
  • Red Hat / Red Hat build of Keycloak 26.4
    Fixed in 26.4-14
  • Red Hat / Red Hat build of Keycloak 26.4
    Fixed in 26.4-14
  • Red Hat / Red Hat build of Keycloak 26.4.11
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References