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GHSA-HJJ8-X8WC-9CJ2

Vulnerability from github – Published: 2026-08-26 18:31 – Updated: 2026-08-26 18:31
VLAI
Details

The Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'frm_user_id' parameter in all versions up to, and including, 6.33.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. By forging frm_user_id to match an administrator's user ID — discoverable via the public WordPress REST API — an unauthenticated attacker causes wp_kses_post() to serve as the only output filter, which preserves the injected payload structurally intact; the plugin's admin JavaScript then decodes and executes it automatically on page load.

Severity
7.2 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
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{
  "affected": [],
  "aliases": [
    "CVE-2026-18331"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-26T07:16:45Z",
    "severity": "HIGH"
  },
  "details": "The Formidable Forms \u2013 WordPress Form Builder for Contact Forms, Calculators, Quizzes \u0026 More plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the \u0027frm_user_id\u0027 parameter in all versions up to, and including, 6.33.1 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. By forging frm_user_id to match an administrator\u0027s user ID \u2014 discoverable via the public WordPress REST API \u2014 an unauthenticated attacker causes wp_kses_post() to serve as the only output filter, which preserves the injected payload structurally intact; the plugin\u0027s admin JavaScript then decodes and executes it automatically on page load.",
  "id": "GHSA-hjj8-x8wc-9cj2",
  "modified": "2026-08-26T18:31:54Z",
  "published": "2026-08-26T18:31:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-18331"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/controllers/FrmEntriesController.php#L752"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/controllers/FrmHooksController.php#L69"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/models/FrmEntry.php#L819"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/models/FrmEntry.php#L846"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/models/FrmEntry.php#L982"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/models/fields/FrmFieldType.php#L1830"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/models/fields/FrmFieldType.php#L2083"
    },
    {
      "type": "WEB",
      "url": "https://plugins.trac.wordpress.org/browser/formidable/trunk/js/formidable_admin.js#L1"
    },
    {
      "type": "WEB",
      "url": "https://www.wordfence.com/threat-intel/vulnerabilities/id/f03b09ad-257c-48c9-8ecc-36f60f178f80?source=cve"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}



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