{"id":"CVE-2026-18203","aliases":["EUVD-2026-51484","GHSA-wx5m-whr8-48h5"],"status":"published","title":"Keycloak-services: keycloak-services: group policy extendchildren matches sibling group path prefixes","description":"A flaw was found in the group policy evaluation logic of Keycloak, an identity and access management solution. When a group policy is set to extend permissions to child groups, the system incorrectly uses a simple text-based prefix check to verify group membership. This allows a user who belongs to a different group with a similar starting name to bypass security checks and gain unauthorized access to administrative functions or protected resources.","severity":{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.0039,"percentile":0.33459,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-863"],"published":"2026-07-31T07:08:26Z","modified":"2026-11-06T17:34:07Z","products":[{"vendor":"red hat","product":"red hat build of keycloak 26.6"},{"vendor":"red hat","product":"red hat build of keycloak 26.6.8"},{"vendor":"red hat","product":"red hat data grid 8"},{"vendor":"red hat","product":"red hat jboss enterprise application platform expansion pack"},{"vendor":"red hat","product":"red hat single sign-on 7"},{"vendor":"redhat","product":"build_of_keycloak"}],"references":[{"url":"https://access.redhat.com/errata/RHSA-2026:95761","tags":["vendor-advisory","x_refsource_REDHAT"]},{"url":"https://access.redhat.com/errata/RHSA-2026:95762","tags":["vendor-advisory","x_refsource_REDHAT"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-18203","tags":["vdb-entry","x_refsource_REDHAT","Vendor Advisory"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2508291","tags":["issue-tracking","x_refsource_REDHAT","Issue Tracking","Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-18203"},{"url":"https://github.com/advisories/GHSA-wx5m-whr8-48h5"}],"sources":{"cve":[{"id":"CVE-2026-18203","title":"Keycloak-services: keycloak-services: group policy extendchildren matches sibling group path prefixes","description":"A flaw was found in the group policy evaluation logic of Keycloak, an identity and access management solution. When a group policy is set to extend permissions to child groups, the system incorrectly uses a simple text-based prefix check to verify group membership. This allows a user who belongs to a different group with a similar starting name to bypass security checks and gain unauthorized access to administrative functions or protected resources.","status":"published","published":"2026-07-31T07:08:26.588Z","modified":"2026-11-06T17:34:07.244Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-863"],"updated_at":"2026-11-06T18:59:08.498645Z"}],"euvd":[{"id":"EUVD-2026-51484","description":"A flaw was found in the group policy evaluation logic of Keycloak, an identity and access management solution. When a group policy is set to extend permissions to child groups, the system incorrectly uses a simple text-based prefix check to verify group membership. This allows a user who belongs to a different group with a similar starting name to bypass security checks and gain unauthorized access to administrative functions or protected resources.","status":"published","published":"2026-07-31T07:08:26Z","modified":"2026-11-06T17:34:07Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium"}],"updated_at":"2026-11-06T18:05:39.47551Z"}],"ghsa":[{"id":"GHSA-wx5m-whr8-48h5","title":"A flaw was found in the group policy evaluation logic of Keycloak, an identity and access...","description":"A flaw was found in the group policy evaluation logic of Keycloak, an identity and access management solution. When a group policy is set to extend permissions to child groups, the system incorrectly uses a simple text-based prefix check to verify group membership. This allows a user who belongs to a different group with a similar starting name to bypass security checks and gain unauthorized access to administrative functions or protected resources.","status":"published","published":"2026-07-31T09:31:18Z","modified":"2026-11-06T18:35:32Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium"}],"cwes":["CWE-863"],"updated_at":"2026-11-06T19:01:27.658277Z"}],"nvd":[{"id":"CVE-2026-18203","description":"A flaw was found in the group policy evaluation logic of Keycloak, an identity and access management solution. When a group policy is set to extend permissions to child groups, the system incorrectly uses a simple text-based prefix check to verify group membership. This allows a user who belongs to a different group with a similar starting name to bypass security checks and gain unauthorized access to administrative functions or protected resources.","status":"published","published":"2026-07-31T08:16:27.01Z","modified":"2026-11-06T18:18:09.537Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","level":"medium","assessor":"secondary"}],"cwes":["CWE-863"],"updated_at":"2026-11-06T20:01:12.716992Z"}]}}