Problem
After the announcements in the previous posts about the security vulnerabilities in Rails 3.0.3, you would like to update your application and deploy with the latest 3.0.4 version.

Solution

• Change your Gemfile to replace
  gem 'rails', '3.0.3'
  with
  gem 'rails', '3.0.4'
• Run:
  bundle update rails
• Remove the old gems by using:
  git status
  and then
  git rm name_of_3.0.3_gem
• Add the new gems to your git
  git add vendor/cache
• Check in to your repository the new files
  git commit vendor/cache -m 'upgrade to rails 3.0.4'
• Make sure that you also check in both your Gemfile and Gemfile.lock into your git repository
  git commit Gemfile Gemfile.lock -m 'update Gemfiles to use 3.0.4'
  otherwise when you try to deploy you will see the error:
  You have modified your Gemfile in development but did not check the resulting snapshot (Gemfile.lock) into version control
• push everything to your git repository:
  git push
• Deploy your application with capistrano as usual:
  cap deploy
• Your new gems for 3.0.4 should be installed on the share/bundle folder