curl --request GET \
  --url https://api.gcore.com/cloud/v1/instances/{project_id}/{region_id}/{instance_id}/securitygroups \
  --header 'Authorization: <api-key>'

{
  "count": 1,
  "results": [
    {
      "id": "2bf3a5d7-9072-40aa-8ac0-a64e39427a2c",
      "name": "Test"
    }
  ]
}