Ajenti: Privilege escalation to root via unauthenticated/unauthorized plugin install task

Ajenti is a Linux & BSD modular server admin panel. Prior to version 2.2.16, any authenticated user can call /api/core/tasks/start to enqueue InstallPlugin, UnInstallPlugin, or UpgradeAll from plugins/plugins/tasks.py without plugin-management authorization. InstallPlugin and UnInstallPlugin construct a pip package specification from unvalidated name and version fields, and the task worker invokes pip while running as root. A low-privileged user can therefore select or manipulate a package installed with root privileges and can install, remove, or upgrade plugins without administrative permission, resulting in root code execution and full host compromise. This issue is fixed in version 2.2.16.