instance method sanitize

Sanitizes HTML input, stripping all but known-safe tags and attributes.

It also strips href / src attributes with unsafe protocols like javascript:, while also protecting against attempts to use Unicode, ASCII, and hex character references to work around these protocol filters.

The default sanitizer is Rails::HTML5::SafeListSanitizer. See Rails HTML Sanitizers for more information.

Custom sanitization rules can also be provided.

Warning: Adding disallowed tags or attributes to the allowlists may introduce vulnerabilities into your application. Please rely on the default allowlists whenever possible, because they are curated to maintain security and safety. If you think that the default allowlists should be expanded, please open an issue on the rails-html-sanitizer project.

Please note that sanitizing user-provided text does not guarantee that the resulting markup is valid or even well-formed.

Options

:tags

An array of allowed tags.

:attributes

An array of allowed attributes.

:scrubber

A Rails::HTML scrubber or Loofah::Scrubber object that defines custom sanitization rules. A custom scrubber takes precedence over custom tags and attributes.

Examples

Normal use

<%= sanitize @comment.body %>

Providing custom lists of permitted tags and attributes

<%= sanitize @comment.body, tags: %w(strong em a), attributes: %w(href) %>

Providing a custom Rails::HTML scrubber

class CommentScrubber < Rails::HTML::PermitScrubber
  def initialize
    super
    self.tags = %w( form script comment blockquote )
    self.attributes = %w( style )
  end

  def skip_node?(node)
    node.text?
  end
end

<%= sanitize @comment.body, scrubber: CommentScrubber.new %>

See Rails HTML Sanitizer for documentation about Rails::HTML scrubbers.

Providing a custom Loofah::Scrubber

scrubber = Loofah::Scrubber.new do |node|
  node.remove if node.name == 'script'
end

<%= sanitize @comment.body, scrubber: scrubber %>

See Loofah’s documentation for more information about defining custom Loofah::Scrubber objects.

Global Configuration

To set the default allowed tags or attributes across your application:

# In config/application.rb
config.action_view.sanitized_allowed_tags = ['strong', 'em', 'a']
config.action_view.sanitized_allowed_attributes = ['href', 'title']

The default, starting in Rails 7.1, is to use an HTML5 parser for sanitization (if it is available, see NOTE below). If you wish to revert back to the previous HTML4 behavior, you can do so by setting the following in your application configuration:

# In config/application.rb
config.action_view.sanitizer_vendor = Rails::HTML4::Sanitizer

Or, if you’re upgrading from a previous version of Rails and wish to opt into the HTML5 behavior:

# In config/application.rb
config.action_view.sanitizer_vendor = Rails::HTML5::Sanitizer

NOTE: Rails::HTML5::Sanitizer is not supported on JRuby, so on JRuby platforms Rails will fall back to using Rails::HTML4::Sanitizer.