CVE-2026-41166: OpenRemote has Improper Access Control via updateUserRealmRoles function

Summary A user who has write:admin in one Keycloak realm can call the Manager API to update Keycloak realm roles for users in another realm, including master. The handler uses the {realm} path segment when talking to the identity provider but does not check that the caller may administer that realm. This could result in a privilege escalation to master realm administrator if the attacker controls any user in master realm.

Details In manager/src/main/java/org/openremote/manager/security/UserResourceImpl.java, there is no check to validate if the caller should be able to administer a realm they're trying to update.

340:353:manager/src/main/java/org/openremote/manager/security/UserResourceImpl.java @Override public void updateUserRealmRoles(RequestParams requestParams, String realm, String userId, String[] roles) { try { identityService.getIdentityProvider().updateUserRealmRoles( realm, userId, roles); } catch (ClientErrorException ex) { ex.printStackTrace(System.out); throw new WebApplicationException(ex.getCause(), ex.getResponse().getStatus()); } catch (Exception ex) { throw new WebApplicationException(ex); } }

PoC 1. Create a new Keycloak realm other than master. Add a user and grant that user the OpenRemote client role write:admin. Remember the realm name (call it NEWREALM). 2. In Keycloak realm master, pick a low-privilege user (no admin realm role). Copy that user’s UUID (<master-user-uuid>). 3. Authenticate as the user from step 1 and obtain a Bearer access token (<token>) for NEWREALM. 4. Replace placeholders and run: bash curl -k -X PUT "https://<host>/api/<NEWREALM>/user/master/userRealmRoles/<master-user-uuid>" \ -H "Authorization: Bearer <token>" \ -H "Content-Type: application/json" \ -d '["admin"]' 5. In the Keycloak Admin Console, realm master, that user, Role mapping. Confirm the admin realm role is assigned. Impact An attacker with the OpenRemote client role write:admin in any realm can call this API with {realm} set to another realm (for example master) and change Keycloak realm roles for users there. That can grant admin on master to a user UUID they target, which gives Keycloak administrator access for the master realm.