The Innovative Form Builder <= 1.5.1 - Authenticated (Custom+) Arbitrary File Upload via 'allowedFileExtensions' Configuration + Public /form/submission/ Multipart Upload

The The Innovative Form Builder – IvyForms plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 1.5.1 via the filterFiletypeAndExt function. This is due to insufficient file type validation due to the absence of a dangerous-extension denylist in the allowed-extensions sanitizer and deliberate override of WordPress's native MIME and extension defences via a registered wp_check_filetype_and_ext filter. This makes it possible for authenticated attackers, with custom-level access and above, to upload files that may be executable, which makes remote code execution possible. An authenticated attacker with the custom add_edit_forms capability must first configure a File Upload field with a dangerous extension (e.g., php) in the allowed-extensions list; once that form is published, any unauthenticated visitor can trigger the actual file upload via the publicly accessible /wp-json/ivyforms/v1/form/submission/ REST route.