The Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'frmuserid' 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 frmuserid to match an administrator's user ID — discoverable via the public WordPress REST API — an unauthenticated attacker causes wpksespost() 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.

The Formidable Forms WordPress plugin before 6.2 unserializes user input, which could allow anonymous users to perform PHP Object Injection when a suitable gadget is present.

The Formidable PRO2PDF WordPress Plugin, version < 3.11, is affected by an authenticated SQL injection vulnerability in the ‘fieldmap’ parameter in the fpropdfexportfile action.

The Formidable Forms WordPress plugin before 6.1 uses several potentially untrusted headers to determine the IP address of the client, leading to IP Address spoofing and bypass of anti-spam protections.

An arbitrary file upload vulnerability in formidable v3.1.4 allows attackers to execute arbitrary code via a crafted filename. NOTE: some third parties dispute this issue because the product has common use cases in which uploading arbitrary files is the desired behavior. Also, there are configuration options in all versions that can change the default behavior of how files are handled.

The Formidable Forms WordPress plugin before 6.3.1 does not adequately authorize the user or validate the plugin URL in its functionality for installing add-ons. This allows a user with a role as low as Subscriber to install and activate arbitrary plugins of arbitrary versions from the WordPress.org plugin repository onto the site, leading to Remote Code Execution.

The Formidable Forms WordPress plugin before 6.14.1 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfilteredhtml capability is disallowed (for example in multisite setup).

The formidable plugin before 4.02.01 for WordPress has unsafe deserialization.

The Formidable Form Builder WordPress plugin before 4.09.05 allows to inject certain HTML Tags like <audio>,<video>,<img>,<a> and<button>.This could allow an unauthenticated, remote attacker to exploit a HTML-injection byinjecting a malicous link. The HTML-injection may trick authenticated users to follow the link. If the Link gets clicked, Javascript code can be executed. The vulnerability is due to insufficient sanitization of the "data-frmverify" tag for links in the web-based entry inspection page of affected systems. A successful exploitation incomibantion with CSRF could allow the attacker to perform arbitrary actions on an affected system with the privileges of the user. These actions include stealing the users account by changing their password or allowing attackers to submit their own code through an authenticated user resulting in Remote Code Execution. If an authenticated user who is able to edit Wordpress PHP Code in any kind, clicks the malicious link, PHP code can be edited.

The Formidable Form Builder – Contact Form, Survey & Quiz Forms Plugin for WordPress plugin before 5.0.07 does not sanitise and escape its Form's Labels, allowing high privileged users to perform Cross-Site Scripting attacks even when the unfilteredhtml capability is disallowed