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💎 RubyGems

GHSA-2x5m-9ch4-qgrr

rails-html-sanitizer has XSS vulnerability with certain configurations

Also known asCVE-2024-53987
Published
Dec 2, 2024
Updated
Dec 3, 2024
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk34th percentile-1.54%
0.00%0.83%1.66%2.49%0.2%0.4%Dec 25Apr 26Jun 26

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected
💎rails-html-sanitizer

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

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: < 1.6.0
  • Fixed versions: 1.6.1

Impact

A possible XSS vulnerability with certain configurations of Rails::HTML::Sanitizer may allow an attacker to inject content if HTML5 sanitization is enabled and the application developer has overridden the sanitizer's allowed tags in the following way:

  • the "style" element is explicitly allowed
  • the "svg" or "math" element is not allowed

Code is only impacted if Rails is configured to use HTML5 sanitization, please see documentation for config.action_view.sanitizer_vendor and config.action_text.sanitizer_vendor for more information on these configuration options.

The default configuration is to disallow all of these elements. Code is only impacted if allowed tags are being overridden. Applications may be doing this in a few different ways:

  1. using application configuration to configure Action View sanitizers' allowed tags:
# In config/application.rb
config.action_view.sanitized_allowed_tags = ["style"]

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

  1. using a :tags option to the Action View helper sanitize:
<%= sanitize @comment.body, tags: ["style"] %>

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

  1. setting Rails::HTML5::SafeListSanitizer class attribute allowed_tags:
# class-level option
Rails::HTML5::SafeListSanitizer.allowed_tags = ["style"]

(note that this class may also be referenced as Rails::Html::SafeListSanitizer)

  1. using a :tags options to the Rails::HTML5::SafeListSanitizer instance method sanitize:
# instance-level option
Rails::HTML5::SafeListSanitizer.new.sanitize(@article.body, tags: ["style"])

(note that this class may also be referenced as Rails::Html::SafeListSanitizer)

  1. setting ActionText::ContentHelper module attribute allowed_tags:
ActionText::ContentHelper.allowed_tags = ["style"]

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

Workarounds

Any one of the following actions will work around this issue:

References

Credit

This vulnerability was responsibly reported by So Sakaguchi (mokusou) and taise.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemsrails-html-sanitizer≥ 1.6.0&&< 1.6.11.6.1

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for rails-html-sanitizer. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update rails-html-sanitizer to 1.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-2x5m-9ch4-qgrr is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether GHSA-2x5m-9ch4-qgrr is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-2x5m-9ch4-qgrr. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## 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: < 1.6.0 * Fixed versions: 1.6.1 ## Impact A possible XSS vulnerability with certain configurations of Rails::HTML::Sanitizer may allow an attacker to inject content if HTML5 sanitization is enabled and the application developer has overridden the sanitizer's allowed tags in the following way: - the "style" element is explicitly allowed - the "svg" or "math" element is not allowed Code is only impacted if Rai
O3 Security · Impact-Aware SCA

Is GHSA-2x5m-9ch4-qgrr in your dependencies?

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