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Findings

CVE-2026-4634

A flaw was found in Keycloak.

Published Apr 2, 2026 · updated Oct 6, 2026 · redhat build of keycloak

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.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 2, 2026 · NIST NVD

    Detected

    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.

  2. Oct 6, 2026 · NIST NVD

    Updated

    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.

Affected

  • cpe redhat/build of keycloakversion unspecified
  • cpe redhat/build of keycloak26.2
  • cpe redhat/build of keycloak26.2.15
  • cpe redhat/build of keycloak26.4
  • cpe redhat/build of keycloak26.4.11

Sources

  • CVE.orgVulnerability recordCVE-2026-4634

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2026-4634

    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 process

    nvd.nist.gov

References