Versions of Rails::Html::Sanitizer prior to version 1.4.3 are vulnerable to XSS with certain configurations of Rails::Html::Sanitizer which allows an attacker to inject content when the application developer has overridden the sanitizer's allowed tags to allow both
style elements. Code is only impacted if allowed tags are being overridden.
This may be done via application configuration:
ruby# In config/application.rbconfig.action_view.sanitized_allowed_tags = ["select", "style"]
Or it may be done with a
:tags option to the Action View helper
<%= sanitize @comment.body, tags: ["select", "style"] %>
It may also be done with Rails::Html::SafeListSanitizer directly:
ruby# class-level optionRails::Html::SafeListSanitizer.allowed_tags = ["select", "style"] or with
ruby# instance-level optionRails::Html::SafeListSanitizer.new.sanitize(@article.body, tags: ["select", "style"])
All users overriding the allowed tags by any of the above mechanisms to include both "select" and "style" are recommended to upgrade immediately. A workaround for this issue can be applied by removing either
style from the overridden allowed tags.