{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "solspace/craft-freeform"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.23"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-15T22:40:42Z",
    "nvd_published_at": null,
    "severity": "LOW"
  },
  "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\u0027t 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\u003c?php\n\nrequire \u0027vendor/autoload.php\u0027;\n\n$reader = \\PhpOffice\\PhpSpreadsheet\\IOFactory::createReader(\"Xlsx\");\n$spreadsheet = $reader-\u003eload(__DIR__ . \u0027/book.xlsx\u0027);\n\n$writer = new \\PhpOffice\\PhpSpreadsheet\\Writer\\Html($spreadsheet);\nprint($writer-\u003egenerateHTMLAll());\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.",
  "id": "GHSA-44jg-mv3h-wj6g",
  "modified": "2026-01-15T22:40:42Z",
  "published": "2026-01-15T22:40:42Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "solspace/craft-freeform Vulnerable to XSS in `PhpSpreadsheet` HTML Writer Due to Unsanitized Styling Data"
}