Nezha Monitoring: RoleMember can run shell on every server (cross-tenant RCE) via POST /api/v1/cron

Nezha Monitoring is a self-hostable, lightweight, servers and websites monitoring and O&M tool. From version 1.4.0 to before version 2.0.8, a RoleMember user can create a scheduled cron task with Cover=CronCoverAll, Servers=[] and an arbitrary Command. At every tick of the scheduler, the dashboard pushes that command to every server in the global ServerShared map — including servers that belong to other tenants (admin's servers, other members' servers). Each agent runs the command and returns the output, which is then sent to the attacker's own NotificationGroup → attacker-controlled webhook. This issue has been patched in version 2.0.8.