{"id":"BIT-keycloak-2026-4634","summary":"Keycloak: keycloak: denial of service via excessive processing of openid connect scope parameters","details":"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.","aliases":["CVE-2026-4634","GHSA-h4wv-g838-66g3"],"modified":"2026-09-08T08:48:06.811563105Z","published":"2026-08-25T11:42:30.857Z","database_specific":{"severity":"High","cpes":["cpe:2.3:a:redhat:build_of_keycloak:*:*:*:*:text-only:*:*:*","cpe:2.3:a:keycloak:keycloak:*:*:*:*:*:*:*:*"]},"references":[{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:6475"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:6476"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:6477"},{"type":"ADVISORY","url":"https://access.redhat.com/errata/RHSA-2026:6478"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-4634"},{"type":"ADVISORY","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2450250"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-4634"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4634.json"}],"affected":[{"package":{"name":"keycloak","ecosystem":"Bitnami","purl":"pkg:bitnami/keycloak"},"ranges":[{"type":"SEMVER","events":[{"introduced":"26.2.0"},{"fixed":"26.2.1"},{"introduced":"26.2.15"},{"fixed":"26.3.0"},{"introduced":"26.4.0"},{"fixed":"26.4.1"},{"introduced":"26.4.11"},{"fixed":"26.5.0"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/keycloak/BIT-keycloak-2026-4634.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}],"schema_version":"1.9.0"}