Rails Html Sanitizers Cross-site Scripting

# Possible XSS Vulnerability in Rails::Html::SanitizerThere is a possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer.This vulnerability has been assigned the CVE identifier CVE-2022-32209.Versions Affected: ALLNot affected: NONEFixed Versions: v1.4.3## ImpactA possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer may allow an attacker to inject content if the application developer has overridden the sanitizer's allowed tags to allow both `select` and `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"]```see https://guides.rubyonrails.org/configuring.html#configuring-action-viewOr it may be done with a `:tags` option to the Action View helper `sanitize`:```<%= sanitize @comment.body, tags: ["select", "style"] %>```see https://api.rubyonrails.org/classes/ActionView/Helpers/SanitizeHelper.html#method-i-sanitizeOr it may be done with Rails::Html::SafeListSanitizer directly:```ruby# class-level optionRails::Html::SafeListSanitizer.allowed_tags = ["select", "style"]```or```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" should either upgrade or use one of the workarounds immediately.## ReleasesThe FIXED releases are available at the normal locations.## WorkaroundsRemove either `select` or `style` from the overridden allowed tags.## CreditsThis vulnerability was responsibly reported by [windshock](https://hackerone.com/windshock?type=user). (2022-06-24, CVE-2022-32209)

Cross site scripting is an attack where a web page executes code that is injected by an adversary. It usually appears, when users input is presented. This attack can be used to impersonate a user, take over control of the session, or even steal API keys.

The attack can be executed e.g. when you application injects the request parameter directly into the HTML code of the page returned to the user:

https://server.com/confirmation?message=Transaction+Complete

what results in:

<span>Confirmation: Transaction Complete</span>

In that case the message can be modified to become a valid Javascript code, e.g.:

https://server.com/confirmation?message=<script>dangerous javascript code here</script>

and it will be executed locally by the user's browser with full access to the user's personal application/browser data:

<span>Confirmation: <script>dangerous javascript code here</script></span>