Kirki <= 6.1.1 - Authenticated (Editor+) Path Traversal to Arbitrary File Read via 'data' Parameter

The Kirki – Freeform Page Builder, Website Builder & Customizer plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 6.1.1 via the 'data' parameter parameter. This makes it possible for authenticated attackers, with editor-level access and above, to read the contents of arbitrary files on the server, which can contain sensitive information. The intended strpos()-based guard against leaving the uploads directory is bypassed by crafting a URL that includes the uploads base path as a substring while embedding directory traversal sequences, such as /wp-content/uploads/../../wp-config.php.