Description
A flaw was found in Keycloak. A missing authorization check in the GroupResource.addChild() endpoint within the Admin REST API allows an authenticated user with limited administrative privileges to reparent any existing group. When Fine-Grained Admin Permissions v2 (FGAPv2) is enabled, an attacker with management rights over a single low-privilege group can reparent a highly privileged group (such as one possessing the realm-admin role) under their managed group. Because group permissions follow a hierarchical structure, this action unauthorizedly grants the attacker management and password-reset capabilities over the members of the targeted privileged group. An attacker can exploit this to reset an administrator's password, compromise the account, and achieve a full realm takeover, leading to a complete compromise of confidentiality, integrity, and availability.
CVSS breakdown
References
- VENDOR_ADVISORYhttps://access.redhat.com/errata/RHSA-2026:30049
- VENDOR_ADVISORYhttps://access.redhat.com/errata/RHSA-2026:30050
- VENDOR_ADVISORYhttps://access.redhat.com/errata/RHSA-2026:30083
- VENDOR_ADVISORYhttps://access.redhat.com/errata/RHSA-2026:30084
- VENDOR_ADVISORYhttps://access.redhat.com/security/cve/CVE-2026-9099
- MISChttps://bugzilla.redhat.com/show_bug.cgi?id=2480182