Formidable Forms <= 6.1.2 - Unauthenticated PHP Object Injection

9.8
Deserialization of Untrusted Data
CVE CVE-2023-1405
CVSS 9.8 (Critical)
Publicly Published April 6, 2023
Last Updated April 12, 2023
Researcher Nguyen Huu Do

Description

The Formidable Forms plugin for WordPress is vulnerable to PHP Object Injection in versions up to, and including, 6.1.2 via deserialization of untrusted input from form submissions. This allows unauthenticated attackers to inject a PHP Object. No POP chain is present in the vulnerable plugin. If a POP chain is present via an additional plugin or theme installed on the target system, it could allow the attacker to delete arbitrary files, retrieve sensitive data, or execute code.

References

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Vulnerability Details for Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More

Software Type Plugin
Software Slug formidable (view on wordpress.org)
Patched? Yes
Remediation Update to version 6.2, or a newer patched version
Affected Version
  • <= 6.1.2
Patched Version
  • 6.2

Recent vulnerabilities in Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More

# Title CVE ID CVSS Researchers Date
1 Formidable Forms <= 6.34 - Unauthenticated Content Injection CVE-2026-85641 5.3 Karthik Ramakrishnan September 14, 2026
2 Formidable Forms <= 6.34 - Unauthenticated Arbitrary Shortcode Execution CVE-2026-19857 6.5 Jakub Herman September 14, 2026
3 Formidable Forms <= 6.33.1 - Unauthenticated Stored Cross-Site Scripting via 'frm_user_id' Parameter CVE-2026-18331 7.2 daroo August 25, 2026
4 Formidable Forms <= 6.32.0 - Unauthenticated Payment Bypass CVE-2026-11361 5.3 Yaswanth Reddy Sunkara June 25, 2026
5 Formidable Forms <= 6.28 - Unauthenticated Payment Amount Manipulation via 'item_meta' Parameter CVE-2026-2888 5.3 Michael Iden (Mickhat) March 12, 2026
6 Formidable Forms <= 6.28 - Missing Authorization to Unauthenticated Payment Integrity Bypass via PaymentIntent Reuse CVE-2026-2890 7.5 Andrés Cruciani March 12, 2026
7 Formidable Forms – Contact Form Plugin, Survey, Quiz, Payment, Calculator Form & Custom Form Builder <= 6.16.1.2 - Reflected Cross-Site Scripting via Custom HTML Form Parameter CVE-2024-11188 6.1 mikemyers November 22, 2024
8 Formidable Forms – Contact Form Plugin, Survey, Quiz, Payment, Calculator Form & Custom Form Builder <= 6.14 - Authenticated (Admin+) Stored Cross-Site Scripting CVE-2024-9768 4.4 Krugov Artyom October 31, 2024
9 Formidable Forms <= 6.11.1 - Authenticated (Subscriber+) Stored Cross-Site Scripting CVE-2024-6725 4.9 zer0gh0st July 30, 2024
10 Formidable Forms <= 6.7.2 - Cross-Site Request Forgery to Stored Cross-Site Scripting CVE-2024-0660 6.1 Webbernaut January 26, 2024

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