Language: Python
Label: vulnerable
CWE: CWE-22 \u2014 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Code:
def config():
    config_disabled = (
            app.config['CONFIG_DISABLE'] or
            not valid_user_session(session))
    if request.method == 'GET':
        return json.dumps(g.user_config.__dict__)
    elif request.method == 'PUT' and not config_disabled:
        if 'name' in request.args:
            config_pkl = os.path.join(
                app.config['CONFIG_PATH'],
                request.args.get('name'))
            session['config'] = (pickle.load(open(config_pkl, 'rb'))
                                 if os.path.exists(config_pkl)
                                 else session['config'])
            return json.dumps(session['config'])
        else:
            return json.dumps({})
    elif not config_disabled:
        config_data = request.form.to_dict()
        if 'url' not in config_data or not config_data['url']:
            config_data['url'] = g.user_config.url

        # Save config by name to allow a user to easily load later
        if 'name' in request.args:
            pickle.dump(
                config_data,
                open(os.path.join(
                    app.config['CONFIG_PATH'],
                    request.args.get('name')), 'wb'))

        session['config'] = config_data
        return redirect(config_data['url'])
    else:
        return redirect(url_for('.index'), code=403)