CVE-2026-73648: Rails HTML Sanitizers Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-cj75-f6xr-r4g7",
  "modified" : "2026-08-13T18:00:24Z",
  "published" : "2026-07-21T22:05:28Z",
  "aliases" : [ "CVE-2026-73648" ],
  "summary" : "Rails HTML Sanitizers: Possible XSS vulnerability with certain configurations",
  "details" : "## Summary\n\nThere is a possible cross-site scripting vulnerability in rails-html-sanitizer when the sanitizer is configured to allow an SVG reference element such as `<use>`. See related [GHSA-9wjq-cp2p-hrgf](https://github.com/flavorjones/loofah/security/advisories/GHSA-9wjq-cp2p-hrgf) in Loofah, whose SVG local-reference logic rails-html-sanitizer mirrors.\n\n- Versions affected: `>= 1.0.3, < 1.7.1`\n- Not affected: `< 1.0.3`\n- Fixed versions: `1.7.1`\n\n## Impact\n\n`Rails::HTML::PermitScrubber` restricts SVG reference elements in the `SVG_ALLOW_LOCAL_HREF` collection to local, same-document references, but that restriction covered only the `xlink:href` attribute. Browsers also accept a plain `href` attribute per the SVG 2 spec, and it was not restricted, so those elements could reference arbitrary external documents. SVG `<use>` can load and render external SVG content by reference, and if the referenced document is same-origin and contains scripts, it could execute in the context of the sanitized document. `<feImage>` can load external images, which can be used for tracking.\n\nApplications are impacted only when the allowed tags are overridden to include one of these SVG reference elements, for example `<use>` or `<feImage>`. The default allowed tags do not include these SVG elements, so applications using the default configuration are not affected.\n\n## Workarounds\n\nRemove the SVG reference elements (such as `use` and `feImage`) from the overridden allowed tags. Applications using the default allowed tags are not affected.\n\n## References\n\n- [GHSA-9wjq-cp2p-hrgf: SVG `href` attribute bypasses local-reference restriction in Loofah](https://github.com/flavorjones/loofah/security/advisories/GHSA-9wjq-cp2p-hrgf)\n- [CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')](https://cwe.mitre.org/data/definitions/79.html)\n\n## Credit\n\nFound by maintainer Mike Dalessio during a security audit.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "rails-html-sanitizer"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.0.3"
      }, {
        "fixed" : "1.7.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails-html-sanitizer/security/advisories/GHSA-cj75-f6xr-r4g7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails-html-sanitizer/commit/74dcb8053e6da9921246ce71b06ad9fd65b19586"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/rails/rails-html-sanitizer"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rails/rails-html-sanitizer/releases/tag/v1.7.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-21T22:05:28Z",
    "nvd_published_at" : null
  }
}