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Cross-site Scripting occurrences in Rails Html Sanitizer
rails-html-sanitizer is responsible for sanitizing HTML fragments in Rails applications. Prior to version 1.4.4, there is a possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer due to an incomplete fix of CVE-2022-32209. 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 issue is patched in version 1.4.4. All users overriding the allowed tags to include both "select" and "style" should either upgrade or use this workaround: Remove either "select" or "style" from the overridden allowed tags. NOTE: Code is _not_ impacted if allowed tags are overridden using either the :tags option to the Action View helper method sanitize or the :tags option to the instance method SafeListSanitizer#sanitize. (2022-12-14, CVE-2022-23520)
rails-html-sanitizer is responsible for sanitizing HTML fragments in Rails applications. Prior to version 1.4.4, a 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 in either of the following ways: allow both "math" and "style" elements, or allow both "svg" and "style" elements. Code is only impacted if allowed tags are being overridden. . This issue is fixed in version 1.4.4. All users overriding the allowed tags to include "math" or "svg" and "style" should either upgrade or use the following workaround immediately: Remove "style" from the overridden allowed tags, or remove "math" and "svg" from the overridden allowed tags. (2022-12-14, CVE-2022-23519)
rails-html-sanitizer is responsible for sanitizing HTML fragments in Rails applications. Versions >= 1.0.3, < 1.4.4 are vulnerable to cross-site scripting via data URIs when used in combination with Loofah >= 2.1.0. This issue is patched in version 1.4.4. (2022-12-14, CVE-2022-23518)
Why Cross-site Scripting can be dangerous
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>