Is Formidable Forms safe? Known vulnerabilities and latest version

The Formidable Forms – WordPress Form Builder for Contact Forms, Calculators, Quizzes & More plugin for WordPress is vulnerable to Arbitrary Plugin Installation in all versions up to, and including, 6.35 via the 'file_url' parameter parameter. This is due to insufficient URL prefix validation in validate_url_is_in_s3_bucket() and a permission callback that relies solely on a shared token obtainable by any user with the delegable frm_view_forms capability, without checking install_plugins or activate_plugins capabilities. This makes it possible for authenticated attackers, with subscriber-level access and above, to install arbitrary plugins on the server. Exploitation additionally requires that the site is free-only (Formidable Pro is NOT installed).

The Formidable Forms WordPress plugin before 7.0 does not verify the identity of the caller before recording the timestamp it uses to rate limit payment gateway verification requests, allowing unauthenticated attackers to consume the daily allowance and cause legitimate verification attempts to be refused for the next 24 hours.

The Formidable Forms WordPress plugin before 6.35 does not prevent a request-derived value from reaching the WordPress shortcode parser when it substitutes a supported token into a form's custom HTML, allowing unauthenticated visitors to have arbitrary shortcodes, with attacker-chosen attributes, executed server-side on any page displaying an affected form.

The Formidable Forms WordPress plugin before 6.35 does not restrict who can set the identifier recording which user last edited a form entry, and relies on that identifier when deciding whether to strip HTML from stored entry values, allowing unauthenticated visitors to have markup rendered in the admin entry view that would otherwise be removed, and to attribute their submission to an administrator who never made it.

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.

The Formidable Forms WordPress plugin before 6.32.1 does not properly validate the status of a PayPal subscription payment before marking it complete, allowing unauthenticated users to bypass payment and trigger paid form actions — such as digital content access, license delivery, and membership activation — without being charged.

The Formidable Forms plugin for WordPress is vulnerable to an authorization bypass through user-controlled key in all versions up to, and including, 6.28. This is due to the `frm_strp_amount` AJAX handler (`update_intent_ajax`) overwriting the global `$_POST` data with attacker-controlled JSON input and then using those values to recalculate payment amounts via field shortcode resolution in `generate_false_entry()`. The handler relies on a nonce that is publicly exposed in the page's JavaScript (`frm_stripe_vars.nonce`), which provides CSRF protection but not authorization. This makes it possible for unauthenticated attackers to manipulate PaymentIntent amounts before payment completion on forms using dynamic pricing with field shortcodes, effectively paying a reduced amount for goods or services.

The Formidable Forms plugin for WordPress is vulnerable to a payment integrity bypass in all versions up to, and including, 6.28. This is due to the Stripe Link return handler (`handle_one_time_stripe_link_return_url`) marking payment records as complete based solely on the Stripe PaymentIntent status without comparing the intent's charged amount against the expected payment amount, and the `verify_intent()` function validating only client secret ownership without binding intents to specific forms or actions. This makes it possible for unauthenticated attackers to reuse a PaymentIntent from a completed low-value payment to mark a high-value payment as complete, effectively bypassing payment for goods or services.

Missing Authorization vulnerability in Strategy11 Form Builder Team Formidable Forms allows Exploiting Incorrectly Configured Access Control Security Levels.This issue affects Formidable Forms: from n/a through 5.5.4.

The Formidable Forms – Contact Form Plugin, Survey, Quiz, Payment, Calculator Form & Custom Form Builder plugin for WordPress is vulnerable to POST-Based Reflected Cross-Site Scripting via the Custom HTML Form parameters in all versions up to, and including, 6.16.1.2 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that execute if they can successfully trick a user into performing an action such as clicking on a link.

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 unfiltered_html capability is disallowed (for example in multisite setup).

The Formidable Form Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via multiple parameters submitted during form entries like 'after_html' in versions before 2.05.03 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that execute in a victim's browser.

The Formidable Forms – Contact Form Plugin, Survey, Quiz, Payment, Calculator Form & Custom Form Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the ‘html’ parameter in all versions up to, and including, 6.11.1 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with form editing permissions and Subscriber-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS) vulnerability in Strategy11 Form Builder Team Formidable Forms allows Code Injection.This issue affects Formidable Forms: from n/a through 6.7.

The Formidable Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 6.7.2. This is due to missing or incorrect nonce validation on the update_settings function. This makes it possible for unauthenticated attackers to change form settings and add malicious JavaScript via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.

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 Forms – Contact Form, Survey, Quiz, Payment, Calculator Form & Custom Form Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the name field label and description field label parameter in all versions up to 6.7 (inclusive) due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level access, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. By default, this only affects multi-site installations and installations where unfiltered_html has been disabled. However, in the formidable settings admins can extend form creation, deletion and other management permissions to other user types, which makes it possible for this vulnerability to be exploited by lower level user types as long as they have been granted the proper permissions.

The Formidable Forms plugin for WordPress is vulnerable to HTML injection in versions up to, and including, 6.7. This vulnerability allows unauthenticated users to inject arbitrary HTML code into form fields. When the form data is viewed by an administrator in the Entries View Page, the injected HTML code is rendered, potentially leading to admin area defacement or redirection to malicious websites. CVE-2024-23522 appears to be a duplicate of this issue.

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

Cross-Site Request Forgery (CSRF) vulnerability in Strategy11 Form Builder Team Formidable Forms plugin <= 5.5.6 versions.

The formidable plugin before 4.02.01 for WordPress has unsafe deserialization.