system: You are an expert security code reviewer. You will be shown a source code file along with a multi-select question listing several CWE (Common Weakness Enumeration) categories. Your task is to identify which of the listed CWEs are present in the code.

OUTPUT FORMAT: Respond with the letter(s) of all correct options, sorted alphabetically and comma-separated, wrapped in a single \boxed{...}. Examples: `\boxed{A}` for one correct, `\boxed{A,C}` for two, `\boxed{A,C,E}` for three. Output the boxed answer ONLY -- no explanation, no other text.

user: ```python
import logging
import os
from flask import Flask, request, jsonify

from commons.encryption.encryption_service import EncryptionService
from federated_trainer.service.federated_trainer import FederatedTrainer

from logging.config import dictConfig

dictConfig({
    'version': 1,
    'formatters': {'default': {
        'format': '[%(asctime)s] %(levelname)s in %(module)s: %(message)s',
    }},
    'handlers': {'wsgi': {
        'class': 'logging.StreamHandler',
        'stream': 'ext://flask.logging.wsgi_errors_stream',
        'formatter': 'default'
    }},
    'root': {
        'level': 'INFO',
        'handlers': ['wsgi']
    }
})


def create_app():
    # create and configure the app
    flask_app = Flask(__name__)
    # load the instance config
    # ensure the instance folder exists
    try:
        os.makedirs(flask_app.instance_path)
    except OSError:
        pass
    flask_app.config.from_pyfile('config.py')
    return flask_app


app = create_app()
encryption_service = EncryptionService()
federated_trainer = FederatedTrainer(encryption_service=encryption_service, config=app.config)
logging.info("federated_trainer running")


@app.errorhandler(Exception)
def handle_error(error):
    message = [str(x) for x in error.args]
    status_code = error.status_code
    success = False
    response = {
        'success': success,
        'error': {
            'type': error.__class__.__name__,
            'message': message
        }
    }
    return jsonify(response), status_code


@app.route('/dataowner', methods=['POST'])
def register_data_owner():
    # Json contiene url y puerto a donde esta el cliente que se esta logueando
    data = request.get_json()
    data["host"], data["port"] = request.environ['REMOTE_ADDR'], request.environ['REMOTE_PORT']
    response = federated_trainer.register_data_owner(data)
    return jsonify(response)


@app.route('/dataowner', methods=['GET'])
def get_data_owners():
    return jsonify([str(data_owner) for data_owner in federated_trainer.data_owners])


@app.route('/model', methods=['POST'])
def train_model_async():
    data = request.get_json()
    logging.info("Initializing async model trainig acording to request {}".format(data))
    logging.info("host {} port {}".format(request.environ['REMOTE_ADDR'], request.environ['REMOTE_PORT']))
    # Validate model type
    federated_trainer.process(request.environ['REMOTE_ADDR'], data)
    return jsonify(200)


@app.route('/ping', methods=['POST'])
def ping():
    logging.info("Data {}".format(request.get_json()))
    return jsonify("pong")

```

Which of the following CWE vulnerability categories are present in this code? Multiple options may be correct.

  A) CWE-117: Improper Output Neutralization for Logs
  B) CWE-730: OWASP Top Ten 2004 Category A9 - Denial of Service
  C) CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
  D) CWE-643: Improper Neutralization of Data within XPath Expressions ('XPath Injection')
  E) CWE-295: Improper Certificate Validation
  F) CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Answer: A