{"cve":"CVE-2026-4634","nvd":{"published":"2026-04-02T13:16:27.027","modified":"2026-10-06T17:17:26.293","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5},"cwes":["CWE-1050"],"references":["https://access.redhat.com/errata/RHSA-2026:6475","https://access.redhat.com/errata/RHSA-2026:6476","https://access.redhat.com/errata/RHSA-2026:6477","https://access.redhat.com/errata/RHSA-2026:6478","https://access.redhat.com/errata/RHSA-2026:76128"],"products":["redhat:build_of_keycloak"],"source":"nvd","synced_at":"2026-10-19T22:28:18.033120106+00:00"},"epss":{"cve":"CVE-2026-4634","score":0.00627,"percentile":0.49737,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-h4wv-g838-66g3","url":"https://osv.dev/vulnerability/GHSA-h4wv-g838-66g3","summary":"Keycloak: Application-Level DoS via Scope Processing","modified":"2026-09-10T03:50:44.494029205Z","packages":[{"ecosystem":"Maven","name":"org.keycloak:keycloak-services","purl":"pkg:maven/org.keycloak/keycloak-services","ranges":["<26.5.7"],"fixed":["26.5.7"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}