Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in WP OnlineSupport, Essential Plugin Timeline and History slider allows PHP Local File Inclusion.This issue affects Timeline and History slider: from n/a through 2.3.
Solution:
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.