Medium · published September 15, 2026
The 3D FlipBook – PDF Embedder, PDF Flipbook Viewer, Flipbook Image Gallery plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 1.16.20 via the 'id' parameter. This makes it possible for unauthenticated attackers to extract sensitive data including the full metadata payload of password-protected flipbooks — including title, outline, props, and the serialized data blob containing the underlying PDF file's direct URL — bypassing WordPress post-password confidentiality. Flipbook post IDs can be pre-enumerated via the also-unauthenticated fb3d_send_posts AJAX action, requiring no prior knowledge to target specific flipbooks.