Summary

Under FGAPv2, the ScopeMappedResource and ScopeMappedClientResource
write endpoints (add and delete scope mappings) do not call
requireMapClientScope per role. An admin holding only fine-grained
manage on a single client can attach any realm role — including
realm-admin — to that client's scope mapping, bypassing the
MAP_ROLE_CLIENT_SCOPE permission boundary. When a privileged user
subsequently authenticates through the modified client, the injected
role is projected into the issued token.

Requirements to exploit

FGAPv2 enabled on the realm (adminPermissionsEnabled=true)

Attacker holds fine-grained manage permission on at least one client

A user holding the targeted role (e.g. realm-admin) must
authenticate through the modified client

*Component affected:* org.keycloak.services.resources.admin

*Version affected:* All versions with FGAPv2 support

*Patch available:* no

*File issue trackers?* Yes

*CVSS:* CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:N (7.3 High)

*Embargo:* no

*Acknowledgement:*

Andrej Tomci

Github - @andrejtomci

Steps to reproduce

1. Enable FGAPv2 on the realm (adminPermissionsEnabled=true)
2. Create a delegated admin with fine-grained manage on a single
client — no global manage-clients, no MAP_ROLE_CLIENT_SCOPE on any
privileged role
3. As the delegated admin, call POST
/admin/realms/{r}/clients/{uuid}/scope-mappings/realm with realm-admin
in the roles body — the request succeeds despite no
MAP_ROLE_CLIENT_SCOPE permission
4. Optionally flip fullScopeAllowed=true on the client via PUT
/admin/realms/{r}/clients/{uuid}
5. Authenticate as a user holding realm-admin through the modified client
6. Inspect the issued token — realm-admin is projected into the token
via the injected scope mapping