{"id":"CVE-2026-18203","title":"A flaw was found in the group policy evaluation logic of Keycloak, an identity and access management solution","summary":"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…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N","cwe":["CWE-863"],"published":"2026-07-31","updated":"2026-08-01","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-18203","references":[{"url":"https://access.redhat.com/security/cve/CVE-2026-18203","label":"secalert@redhat.com"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2508291","label":"secalert@redhat.com"}],"tags":["nvd"],"epss":0.00312,"epssPercentile":0.21423,"ingestedAt":"2026-08-01T23:16:02.146Z","slug":"CVE-2026-18203","body":"## Overview\n\nA 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}