CVE-2026-19857: Formidable Forms < 6.35 - Unauthenticated Arbitrary Shortcode Execution via [entry_key] Custom HTML Token
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.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed?
Sites using Formidable Forms versions earlier than 6.35 are exposed where a page displays a form whose custom HTML uses a supported token that can receive request-derived input, including the [entry_key] token.
Does exploitation require an account or user interaction?
No. The issue is unauthenticated and does not require user interaction, but exploitation requires an attacker to reach a page displaying an affected form and to supply a value that reaches the shortcode parser through the token substitution.
What can an attacker do?
An attacker can cause arbitrary WordPress shortcodes, with attacker-chosen attributes, to execute server-side. The reported impact includes limited confidentiality and integrity effects, with no availability impact indicated.