HubSpot All-In-One Marketing <= 11.3.62 - Authenticated (Contributor+) Sensitive Information Exposure via Block Editor Localized Script

The HubSpot All-In-One Marketing – Forms, Popups, Live Chat plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 11.3.62 via the wp_localize_script() / window.leadinConfig JavaScript object. This makes it possible for authenticated attackers, with contributor-level access and above, to extract the site's plaintext HubSpot OAuth refresh token exposed via the window.leadinConfig JavaScript object, which can then be used to access or modify data in the connected HubSpot tenant. Although the refresh token is stored at rest with AES-256-CTR encryption, decryption occurs server-side before the plaintext value is passed to wp_localize_script(), rendering the at-rest encryption ineffective against this exposure path.