using System;

using System.Xml;

public class Program

{

    public static void Main()

    {

        string arquivoXML = "<?xml version=\"1.0\" encoding=\"iso8859-1\"?><parametros><senha><![CDATA[Lcpx&45895048964]]></senha></parametros>";

        XmlDocument xmlDocument1 = new XmlDocument();

        xmlDocument1.LoadXml(arquivoXML);

        XmlNode selectNode = xmlDocument1.SelectNodes("parametros")[0];

        Console.WriteLine(selectNode["senha"].InnerText);

    }

}