24liveblog <= 2.2 - Missing Authorization to Authenticated (Author+) Settings Modification via update_lb24_token AJAX action

The 24liveblog - live blog tool plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the update_lb24_token() AJAX function in versions up to, and including, 2.2. The handler only verifies the 'lb24' nonce (which is generated and localized to any user with block editor access via lb24_block_enqueue_scripts()) and does not verify the user's capabilities or that the supplied user_id belongs to the current user. This makes it possible for authenticated attackers, with author-level access and above, to overwrite the lb24_token, lb24_uid, lb24_refresh_token, and lb24_uname user meta values of any user (including administrators) as well as the corresponding site-wide options, effectively hijacking the plugin's integration with the 24liveblog service.