CVE-2022-23520: rails-html-sanitizer contains an incomplete fix for an XSS vulnerability
Summary
There is a possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer. This is due to an incomplete fix of CVE-2022-32209.
- Versions affected: ALL - Not affected: NONE - Fixed versions: 1.4.4
Impact
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 to allow both "select" and "style" elements.
Code is only impacted if allowed tags are being overridden using either of the following two mechanisms:
1. Using the Rails configuration config.actionview.sanitizedallowtags=:
ruby # In config/application.rb config.actionview.sanitizedallowedtags = ["select", "style"]
(see https://guides.rubyonrails.org/configuring.html#configuring-action-view)
2. Using the class method Rails::Html::SafeListSanitizer.allowedtags=:
ruby # class-level option Rails::Html::SafeListSanitizer.allowedtags = ["select", "style"]
All users overriding the allowed tags by either of the above mechanisms to include both "select" and "style" should either upgrade or use one of the workarounds immediately.
NOTE: Code is not impacted if allowed tags are overridden using either of the following mechanisms:
- the :tags option to the Action View helper method sanitize. - the :tags option to the instance method SafeListSanitizer#sanitize.
Workarounds
Remove either "select" or "style" from the overridden allowed tags.
References
- CWE - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (4.9) - https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-32209 - https://hackerone.com/reports/1654310
Credit
This vulnerability was responsibly reported by Dominic Breuker.
Other sources
A Cross-site scripting vulnerability was found in rails-html-sanitizer. 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 Rails-html-sanitizer 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.
— Red Hat
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.
Affected Software
Event History
Frequently Asked Questions
What is CVE-2022-23520?
CVE-2022-23520 is a Cross-site scripting vulnerability in rails-html-sanitizer.
What configurations of rails-html-sanitizer are affected by CVE-2022-23520?
Certain configurations of rails-html-sanitizer are affected by CVE-2022-23520.
What is the severity of CVE-2022-23520?
CVE-2022-23520 has a severity rating of medium.
How can I fix the CVE-2022-23520 vulnerability?
The CVE-2022-23520 vulnerability can be fixed by updating to version 1.4.4 of rails-html-sanitizer.
Where can I find more information about CVE-2022-23520?
You can find more information about CVE-2022-23520 on the CVE website, NVD, GitHub, Bugzilla, and Red Hat's errata page.