The Countdown, Coming Soon, Maintenance – Countdown & Clock plugin for WordPress is vulnerable to Local File Inclusion in all versions up to, and including, 2.8.9.1 via the createCdObj function. This makes it possible for unauthenticated attackers to include and execute files with the specific filenames on the server, allowing the execution of any PHP code in those files. This can be used to bypass access controls, obtain sensitive data, or achieve code execution in some cases.
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.