The ABC Notation plugin for WordPress is vulnerable to Path Traversal in all versions up to, and including, 6.1.3 via the 'file' attribute of the 'abcjs' shortcode. This makes it possible for authenticated attackers, with Contributor-level access and above, to read the contents of arbitrary files on the server, which can contain sensitive information.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.