Is the use of hidden fields in forms insecure?

Question

For example
Imagine I have the following form

  <%= form_for(@comment) do |f| %>

    <%= f.hidden_field :user_id%>
    <%= f.hidden_field         


        

Answer 1

If the value of those fields is critical, then don't trust the user to return them unchanged. Otherwise, a hidden field is no less or no more secure than a regular visible field - if it's in the HTML, someone can change it.