{"cve":"CVE-2026-18331","nvd":{"published":"2026-08-26T07:16:45.360","modified":"2026-08-26T16:19:05.917","status":"Deferred","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N","score":7.2},"cwes":["CWE-79"],"references":["https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/controllers/FrmEntriesController.php#L752","https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/controllers/FrmHooksController.php#L69","https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/models/FrmEntry.php#L819","https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/models/FrmEntry.php#L846","https://plugins.trac.wordpress.org/browser/formidable/trunk/classes/models/FrmEntry.php#L982"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:17.453294893+00:00"},"epss":{"cve":"CVE-2026-18331","score":0.00494,"percentile":0.42451,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}