The WebToffee WooCommerce PDF Invoices, Packing Slips, Delivery Notes & Shipping Labels plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 4.9.8 via the get_image_src_in_base64 function. This makes it possible for authenticated attackers, with subscriber-level access and above, to read the contents of arbitrary files on the server, which can contain sensitive information. The base64-encoded file contents are embedded into the cached invoice HTML and served directly to the attacker via the plugin's own Print/Download invoice endpoints, which require only a valid nonce and access key.