The Imagely NextGen Gallery plugin for Wordpress prior to version 2.1.57 may execute code from an uploaded malicious file

The Imagely NextGen Gallery plugin for Wordpress prior to version 2.1.57 does not properly validate user input in the cssfile parameter of a HTTP POST request, which may allow an authenticated user to read arbitrary files from the server, or execute arbitrary code on the server in some circumstances (dependent on server configuration).