CVE-2022-23519: Rails html sanitizer Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9h9g-93gc-623h",
  "modified" : "2025-11-04T16:41:59Z",
  "published" : "2022-12-13T17:50:25Z",
  "aliases" : [ "CVE-2022-23519" ],
  "summary" : "Possible XSS vulnerability with certain configurations of rails-html-sanitizer",
  "details" : "## Summary\n\nThere is a possible XSS vulnerability with certain configurations of Rails::Html::Sanitizer.\n\n- Versions affected: ALL\n- Not affected: NONE\n- Fixed versions: 1.4.4\n\n\n## Impact\n\nA 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:\n\n- allow both \"math\" and \"style\" elements,\n- or allow both \"svg\" and \"style\" elements\n\nCode is only impacted if allowed tags are being overridden. Applications may be doing this in four different ways:\n\n1. using application configuration:\n\n  ```ruby\n  # In config/application.rb\n  config.action_view.sanitized_allowed_tags = [\"math\", \"style\"]\n  # or\n  config.action_view.sanitized_allowed_tags = [\"svg\", \"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  <%= sanitize @comment.body, tags: [\"math\", \"style\"] %>\n  <%# or %>\n  <%= sanitize @comment.body, tags: [\"svg\", \"style\"] %>\n  ```\n\n  see https://api.rubyonrails.org/classes/ActionView/Helpers/SanitizeHelper.html#method-i-sanitize\n\n3. using Rails::Html::SafeListSanitizer class method `allowed_tags=`:\n\n  ```ruby\n  # class-level option\n  Rails::Html::SafeListSanitizer.allowed_tags = [\"math\", \"style\"]\n  # or\n  Rails::Html::SafeListSanitizer.allowed_tags = [\"svg\", \"style\"]\n  ```\n\n4. using a `:tags` options to the Rails::Html::SafeListSanitizer instance method `sanitize`:\n\n  ```ruby\n  # instance-level option\n  Rails::Html::SafeListSanitizer.new.sanitize(@article.body, tags: [\"math\", \"style\"])\n  # or\n  Rails::Html::SafeListSanitizer.new.sanitize(@article.body, tags: [\"svg\", \"style\"])\n  ```\n\nAll 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.\n\n\n## Workarounds\n\nRemove \"style\" from the overridden allowed tags, or remove \"math\" and \"svg\" from the overridden allowed tags.\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- https://hackerone.com/reports/1656627\n\n\n## Credit\n\nThis vulnerability was responsibly reported by Dominic Breuker.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "rails-html-sanitizer"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.4.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails-html-sanitizer/security/advisories/GHSA-9h9g-93gc-623h"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2022-23519"
  }, {
    "type" : "WEB",
    "url" : "https://hackerone.com/reports/1656627"
  }, {
    "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-2022-23519.yml"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2023/09/msg00012.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2024/09/msg00045.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-12-13T17:50:25Z",
    "nvd_published_at" : "2022-12-14T17:15:00Z"
  }
}