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7.2

Formidable Forms plugin lets attackers run scripts

CVE-2026-18331 · published 2 months ago
Summary

All versions of the Formidable Forms WordPress plugin up to 6.33.1 allow anyone on the internet to place malicious code into a form field. When an administrator views the affected page, the hidden code runs in their browser, potentially stealing data or changing settings. Update the plugin to the latest version or apply the vendor's patch as soon as possible.

What to do

The CVE record does not list a fixed version. Check the vendor's site or the advisory links below - a fix may already be released.

Affected software
VendorProductAffected versions
strategy11team formidable forms – wordpress form builder for contact forms, calculators, quizzes & more <= 6.33.1
Original advisory text
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...
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.
References
Fix within
Internet-facing 60 days
Internal At next upgrade
  • Not known to be exploited
  • Needs hands-on effort to exploit
  • Gives an attacker partial control
Severity
7.2 High
Exploitation
<1% chance of attack within 30 days
Type
CWE-79Cross-site Scripting (XSS)
Timeline
Published26 Aug 2026
Updated4 Nov 2026
First seen26 Aug 2026
Sources
CVE-2026-18331 · NVD
CVE-2026-18331 · MITRE
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