Ecosyste.ms: Advisories

Security Advisories: GSA_kwCzR0hTQS05aDlnLTkzZ2MtNjIzaM4AAwSh

Possible XSS vulnerability with certain configurations of rails-html-sanitizer

Summary

There is a possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer.

• 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 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. Applications may be doing this in four different ways:

1. using application configuration:

# In config/application.rb
config.action_view.sanitized_allowed_tags = ["math", "style"]
# or
config.action_view.sanitized_allowed_tags = ["svg", "style"]

see https://guides.rubyonrails.org/configuring.html#configuring-action-view

2. using a :tags option to the Action View helper sanitize:

<%= sanitize @comment.body, tags: ["math", "style"] %>
<%# or %>
<%= sanitize @comment.body, tags: ["svg", "style"] %>

see https://api.rubyonrails.org/classes/ActionView/Helpers/SanitizeHelper.html#method-i-sanitize

3. using Rails::Html::SafeListSanitizer class method allowed_tags=:

# class-level option
Rails::Html::SafeListSanitizer.allowed_tags = ["math", "style"]
# or
Rails::Html::SafeListSanitizer.allowed_tags = ["svg", "style"]

4. using a :tags options to the Rails::Html::SafeListSanitizer instance method sanitize:

# instance-level option
Rails::Html::SafeListSanitizer.new.sanitize(@article.body, tags: ["math", "style"])
# or
Rails::Html::SafeListSanitizer.new.sanitize(@article.body, tags: ["svg", "style"])

All users overriding the allowed tags by any of the above mechanisms to include (("math" or "svg") and "style") should either upgrade or use one of the workarounds immediately.

Workarounds

Remove "style" from the overridden allowed tags, or remove "math" and "svg" from the overridden allowed tags.

References

• CWE - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (4.9)
• https://hackerone.com/reports/1656627

Credit

This vulnerability was responsibly reported by Dominic Breuker.

Permalink: https://github.com/advisories/GHSA-9h9g-93gc-623h
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS05aDlnLTkzZ2MtNjIzaM4AAwSh
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: over 1 year ago
Updated: 8 months ago

CVSS Score: 6.1
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Identifiers: GHSA-9h9g-93gc-623h, CVE-2022-23519
References:

• https://github.com/rails/rails-html-sanitizer/security/advisories/GHSA-9h9g-93gc-623h
• https://hackerone.com/reports/1656627
• https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rails-html-sanitizer/CVE-2022-23519.yml
• https://nvd.nist.gov/vuln/detail/CVE-2022-23519
• https://lists.debian.org/debian-lts-announce/2023/09/msg00012.html
• https://github.com/advisories/GHSA-9h9g-93gc-623h

Repository: https://github.com/rails/rails-html-sanitizer
Blast Radius: 34.9

Affected Packages