{"id":"GHSA-638j-pmjw-jq48","summary":"rails-html-sanitizer has XSS vulnerability with certain configurations","details":"## Summary\n\nThere is a possible XSS vulnerability with certain configurations of Rails::HTML::Sanitizer 1.6.0 when used with Rails \u003e= 7.1.0.\n\n* Versions affected: 1.6.0\n* Not affected: \u003c 1.6.0\n* Fixed versions: 1.6.1\n\n## Impact\n\nA 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:\n\n- the \"math\" and \"style\" elements are both explicitly allowed\n\nCode is only impacted if Rails is configured to use HTML5 sanitization, please see documentation for [`config.action_view.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-view-sanitizer-vendor) and [`config.action_text.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-text-sanitizer-vendor) for more information on these configuration options.\n\nThe default configuration is to disallow these elements. Code is only impacted if allowed tags are being overridden. Applications may be doing this in a few different ways:\n\n1. using application configuration to configure Action View sanitizers' allowed tags:\n\n  ```ruby\n  # In config/application.rb\n  config.action_view.sanitized_allowed_tags = [\"math\", \"style\"]\n  ```\n\n  see https://guides.rubyonrails.org/configuring.html#configuring-action-view\n\n2. using a `:tags` option to the Action View helper `sanitize`:\n\n  ```\n  \u003c%= sanitize @comment.body, tags: [\"math\", \"style\"] %\u003e\n  ```\n\n  see https://api.rubyonrails.org/classes/ActionView/Helpers/SanitizeHelper.html#method-i-sanitize\n\n3. setting Rails::HTML5::SafeListSanitizer class attribute `allowed_tags`:\n\n  ```ruby\n  # class-level option\n  Rails::HTML5::SafeListSanitizer.allowed_tags = [\"math\", \"style\"]\n  ```\n\n  (note that this class may also be referenced as `Rails::Html::SafeListSanitizer`)\n\n4. using a `:tags` options to the Rails::HTML5::SafeListSanitizer instance method `sanitize`:\n\n  ```ruby\n  # instance-level option\n  Rails::HTML5::SafeListSanitizer.new.sanitize(@article.body, tags: [\"math\", \"style\"])\n  ```\n\n  (note that this class may also be referenced as `Rails::Html::SafeListSanitizer`)\n\n5. setting ActionText::ContentHelper module attribute `allowed_tags`:\n\n  ```ruby\n  ActionText::ContentHelper.allowed_tags = [\"math\", \"style\"]\n  ```\n\nAll users overriding the allowed tags by any of the above mechanisms to include both \"math\" and \"style\" should either upgrade or use one of the workarounds.\n\n\n## Workarounds\n\nAny one of the following actions will work around this issue:\n\n- Remove \"math\" or \"style\" from the overridden allowed tags,\n- Or, downgrade sanitization to HTML4 (see documentation for [`config.action_view.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-view-sanitizer-vendor) and [`config.action_text.sanitizer_vendor`](https://guides.rubyonrails.org/configuring.html#config-action-text-sanitizer-vendor) for more information).\n\n\n## References\n\n- [CWE - CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (4.9)](https://cwe.mitre.org/data/definitions/79.html)\n- Original report: https://hackerone.com/reports/2519941\n\n## Credit\n\nThis vulnerability was responsibly reported by So Sakaguchi ([mokusou](https://hackerone.com/mokusou)) and [taise](https://hackerone.com/taise).\n","aliases":["CVE-2024-53986"],"modified":"2024-12-03T18:50:30Z","published":"2024-12-02T21:48:24Z","database_specific":{"github_reviewed_at":"2024-12-02T21:48:24Z","nvd_published_at":"2024-12-02T22:15:11Z","cwe_ids":["CWE-79"],"severity":"LOW","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/rails/rails-html-sanitizer/security/advisories/GHSA-638j-pmjw-jq48"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-53986"},{"type":"WEB","url":"https://github.com/rails/rails-html-sanitizer/commit/f02ffbb8465e73920b6de0da940f5530f855965e"},{"type":"PACKAGE","url":"https://github.com/rails/rails-html-sanitizer"},{"type":"WEB","url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rails-html-sanitizer/CVE-2024-53986.yml"}],"affected":[{"package":{"name":"rails-html-sanitizer","ecosystem":"RubyGems","purl":"pkg:gem/rails-html-sanitizer"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.6.0"},{"fixed":"1.6.1"}]}],"versions":["1.6.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/12/GHSA-638j-pmjw-jq48/GHSA-638j-pmjw-jq48.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"}]}