{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-4634", "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "state": "PUBLISHED", "assignerShortName": "redhat", "dateReserved": "2026-03-23T08:41:40.650Z", "datePublished": "2026-04-02T12:44:53.424Z", "dateUpdated": "2026-04-02T15:42:56.405Z"}, "containers": {"cna": {"title": "Keycloak: keycloak: denial of service via excessive processing of openid connect scope parameters", "metrics": [{"other": {"content": {"value": "Important", "namespace": "https://access.redhat.com/security/updates/classification/"}, "type": "Red Hat severity rating"}}, {"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "format": "CVSS"}], "descriptions": [{"lang": "en", "value": "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": [{"vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.4", "collectionURL": "https://catalog.redhat.com/software/containers/", "packageName": "keycloak-rhel9-operator-container", "defaultStatus": "affected", "versions": [{"version": "26.4-14", "lessThan": "*", "versionType": "rpm", "status": "unaffected"}], "cpes": ["cpe:/a:redhat:build_keycloak:26.4::el9"]}, {"vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.4", "collectionURL": "https://catalog.redhat.com/software/containers/", "packageName": "rhbk/keycloak-operator-bundle", "defaultStatus": "affected", "versions": [{"version": "26.4.11-1", "lessThan": "*", "versionType": "rpm", "status": "unaffected"}], "cpes": ["cpe:/a:redhat:build_keycloak:26.4::el9"]}, {"vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.4", "collectionURL": "https://catalog.redhat.com/software/containers/", "packageName": "rhbk/keycloak-rhel9", "defaultStatus": "affected", "versions": [{"version": "26.4-14", "lessThan": "*", "versionType": "rpm", "status": "unaffected"}], "cpes": ["cpe:/a:redhat:build_keycloak:26.4::el9"]}, {"vendor": "Red Hat", "product": "Red Hat build of Keycloak 26.4.11", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "defaultStatus": "unaffected", "packageName": "rhbk/keycloak-rhel9", "cpes": ["cpe:/a:redhat:build_keycloak:26.4::el9"]}], "references": [{"url": "https://access.redhat.com/errata/RHSA-2026:6477", "name": "RHSA-2026:6477", "tags": ["vendor-advisory", "x_refsource_REDHAT"]}, {"url": "https://access.redhat.com/errata/RHSA-2026:6478", "name": "RHSA-2026:6478", "tags": ["vendor-advisory", "x_refsource_REDHAT"]}, {"url": "https://access.redhat.com/security/cve/CVE-2026-4634", "tags": ["vdb-entry", "x_refsource_REDHAT"]}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450250", "name": "RHBZ#2450250", "tags": ["issue-tracking", "x_refsource_REDHAT"]}], "datePublic": "2026-04-02T12:30:00.000Z", "problemTypes": [{"descriptions": [{"cweId": "CWE-1050", "description": "Excessive Platform Resource Consumption within a Loop", "lang": "en", "type": "CWE"}]}], "x_redhatCweChain": "CWE-1050: Excessive Platform Resource Consumption within a Loop", "workarounds": [{"lang": "en", "value": "Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability."}], "timeline": [{"lang": "en", "time": "2026-03-23T08:40:02.817Z", "value": "Reported to Red Hat."}, {"lang": "en", "time": "2026-04-02T12:30:00.000Z", "value": "Made public."}], "credits": [{"lang": "en", "value": "Red Hat would like to thank Slvrqn for reporting this issue."}], "providerMetadata": {"orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749", "shortName": "redhat", "dateUpdated": "2026-04-02T15:42:56.405Z"}, "x_generator": {"engine": "cvelib 1.8.0"}}}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-4634", "lastModified": "2026-04-02T14:16:33.590", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 3.6, "source": "secalert@redhat.com", "type": "Secondary"}]}, "published": "2026-04-02T13:16:27.027", "references": [{"source": "secalert@redhat.com", "url": "https://access.redhat.com/errata/RHSA-2026:6477"}, {"source": "secalert@redhat.com", "url": "https://access.redhat.com/errata/RHSA-2026:6478"}, {"source": "secalert@redhat.com", "url": "https://access.redhat.com/security/cve/CVE-2026-4634"}, {"source": "secalert@redhat.com", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2450250"}], "sourceIdentifier": "secalert@redhat.com", "vulnStatus": "Received", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-1050"}], "source": "secalert@redhat.com", "type": "Secondary"}]}

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