GHSA-cfjx-w229-hgx5 rails-html-sanitizer has XSS vulnerability with certain configurations

• RubyGems rails-html-sanitizer: >= 1.6.0, < 1.6.1 → fixed in 1.6.1

Summary There is a possible XSS vulnerability with certain configurations of Rails::HTML::Sanitizer 1.6.0 when used with Rails >= 7.1.0. • Versions affected: 1.6.0 • Not affected: ``` see https://api.rubyonrails.org/classes/ActionView/Helpers/SanitizeHelper.html#method-i-sanitize 3. setting Rails::HTML5::SafeListSanitizer class attribute `allowed_tags`: ```ruby # class-level option Rails::HTML5::SafeListSanitizer.allowed_tags = ["math", "mtext", "table", "style", "mglyph"] # or Rails::HTML5::SafeListSanitizer.allowed_tags = ["math", "mtext", "table", "style", "malignmark"] ``` (note that this class may also be referenced as `Rails::Html::SafeListSanitizer`) 4. using a `:tags` options to the Rails::HTML5::SafeListSanitizer instance method `sanitize`: ```ruby # instance-level option Rails::HTML5::SafeListSanitizer.new.sanitize(@article.body, tags: ["math", "mtext", "table", "style", "mglyph"]) # or Rails::HTML5::SafeListSanitizer.new.sanitize(@article.body, tags: ["math", "mtext", "table", "style", "malignmark"]) ``` (note that this class may also be referenced as `Rails::Html::SafeListSanitizer`) 5. setting ActionText::ContentHelper module attribute `allowed_tags`: ```ruby ActionText::ContentHelper.allowed_tags = ["math", "mtext", "table", "style", "mglyph"] # or ActionText::ContentHelper.allowed_tags = ["math", "mtext", "table", "style", "malignmark"] ``` All users overriding the allowed tags by any of the above mechanisms to include ("math" and "mtext" and "table" and "style" and ("mglyph" or "malignmark")) should either upgrade or use one of the workarounds. Workarounds Any one of the following actions will work around this issue: • Remove "mglyph" and "malignmark" from the overridden allowed tags, • Or, downgrade sanitization to HTML4 (see documentation for `config.action_view.sanitizer_vendor` and `config.action_text.sanitizer_vendor` for more information). References • CWE - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (4.9) • Original report: https://hackerone.com/reports/2519936 Credit This vulnerability was responsibly reported by So Sakaguchi (mokusou) and taise.