User Access Manager <= 2.3.15 - Unauthenticated Arbitrary File Read via 'uamgetfile' Parameter

The User Access Manager plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 2.3.15 via the 'uamgetfile' parameter parameter. This makes it possible for unauthenticated attackers to read the contents of arbitrary files on the server, which can contain sensitive information. This is possible because when attachment_url_to_postid() returns 0 for a traversal path, the plugin falls back to the global post set by a valid ?attachment_id parameter supplied by the attacker, causing the access check to pass against a legitimate public attachment while the file streamed is the attacker-chosen path.