The Assistant for NextGEN Gallery plugin for WordPress is vulnerable to arbitrary directory deletion due to insufficient file path validation in the /wp-json/nextgenassistant/v1.0.0/control REST endpoint in all versions up to, and including, 1.0.9. This makes it possible for unauthenticated attackers to delete arbitrary directories on the server, which can cause a complete loss of availability.
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.