GHSA-pg8v-g4xq-hww9
MEDIUMRails::Html::Sanitizer vulnerable to Cross-site Scripting
EPSS Exploitation Probability
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
rails-html-sanitizerReal-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
Versions of Rails::Html::Sanitizer prior to version 1.4.3 are vulnerable to XSS with certain configurations of Rails::Html::Sanitizer which allows an attacker to inject content when 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-view
Or 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-sanitize
It may also be done with Rails::Html::SafeListSanitizer directly:
ruby# class-level optionRails::Html::SafeListSanitizer.allowed_tags = ["select", "style"] or with
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" are recommended to upgrade immediately. A workaround for this issue can be applied by removing either select or style from the overridden allowed tags.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | rails-html-sanitizer | all versions | 1.4.3 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
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.
Fix
Update rails-html-sanitizer to 1.4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-pg8v-g4xq-hww9 is resolved across your whole dependency graph.
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.
How O3 protects you
O3 pinpoints whether GHSA-pg8v-g4xq-hww9 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-pg8v-g4xq-hww9. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-pg8v-g4xq-hww9 in your dependencies?
O3 detects GHSA-pg8v-g4xq-hww9 across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.