AR for WooCommerce <= 8.40 - Unauthenticated Path Traversal to Arbitrary File Read via 'file' Parameter

The AR for WooCommerce plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 8.40 via the 'file' parameter parameter. This makes it possible for unauthenticated attackers to read the contents of arbitrary files on the server, which can contain sensitive information. The three intended access controls all fail: valid nonces are freely minted by unauthenticated callers via the nopriv ar_get_fresh_nonce and ar_process_user_image AJAX handlers; the AES-256-CBC encryption key is derived from get_option('ar_licence_key'), which returns false on default free installations and yields a predictable key attackers can use to encrypt their own path payloads; and the Referer check is trivially bypassed because the Referer header is attacker-controlled.