Arbitrary Perl Code Execution via Unvalidated Plugin Parameter in cPanel create_user

Insufficient input validation of the `plugin` parameter of the `create_user` plugin allows arbitrary Perl code execution on behalf of the already authenticated account's system user.

A chmod call in the cPanel Nova plugin's Cpanel::Nova::Connector follows symlinks, allowing setting root permissions on arbitrary system files or directories. That can cause DoS or local privilege escalation when an authenticated cPanel user places a symlink at a user-controlled legacy Nova path under their home directory.

Insufficient input validation of the feature file name in `feature::LOADFEATUREFILE` adminbin call can cause arbitrary file read when a relative file path is passed.