Security Vulnerability

Can you see the security vulnerability in the following snippet of code?

    string returnValue = String.Empty;
    string sql =
        "select description from products where prodID = '"
        + Request.Params["pid"] + "';";
    SqlCommand sqlcmd = new SqlCommand(sql);
    sqlcmd.Connection = sqlConn;
    SqlDataReader sdr = cmd.ExecuteReader();
    if (sdr.Read())
    {
        returnValue = (string)sdr[0];
    }
    sdr.Close();
    return returnValue;