GHSA-44jg-mv3h-wj6g: Solspace/craft freeform Cross-Site Scripting Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-44jg-mv3h-wj6g",
  "modified" : "2026-01-15T22:40:42Z",
  "published" : "2026-01-15T22:40:42Z",
  "aliases" : [ ],
  "summary" : "solspace/craft-freeform Vulnerable to XSS in `PhpSpreadsheet` HTML Writer Due to Unsanitized Styling Data",
  "details" : "### Summary\n_Short summary of the problem. Make the impact and severity as clear as possible. For example: An unsafe deserialization vulnerability allows any unauthenticated user to execute arbitrary code on the server._\n\n\\PhpOffice\\PhpSpreadsheet\\Writer\\Html doesn't sanitize spreadsheet styling information such as font names, allowing an attacker to inject arbitrary JavaScript on the page.\n\n### Details\n_Give all details on the vulnerability. Pointing to the incriminated source code is very helpful for the maintainer._\n\nSee https://github.com/advisories/GHSA-wgmf-q9vr-vww6\n\n### PoC\n_Complete instructions, including specific configuration details, to reproduce the vulnerability._\n\nExample target script:\n\n```\n<?php\n\nrequire 'vendor/autoload.php';\n\n$reader = \\PhpOffice\\PhpSpreadsheet\\IOFactory::createReader(\"Xlsx\");\n$spreadsheet = $reader->load(__DIR__ . '/book.xlsx');\n\n$writer = new \\PhpOffice\\PhpSpreadsheet\\Writer\\Html($spreadsheet);\nprint($writer->generateHTMLAll());\n```\n\nSave this file in the same directory:\n\n[book.xlsx](https://github.com/PHPOffice/PhpSpreadsheet/files/15212797/book.xlsx)\n\nOpen index.php in a web browser. An alert should be displayed.\n\n### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nFull takeover of the session of users viewing spreadsheet files as HTML.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "solspace/craft-freeform"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.23"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-wgmf-q9vr-vww6"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/solspace/craft-freeform/security/advisories/GHSA-44jg-mv3h-wj6g"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/solspace/craft-freeform"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/solspace/craft-freeform/releases/tag/v4.1.23"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-15T22:40:42Z",
    "nvd_published_at" : null
  }
}