CVE-2026-100394: Nezha Monitoring: Whole-instance DoS in Nezha dashboard: a member can crash the process for every tenant

A single low-privilege RoleMember can take the entire Nezha dashboard offline, and with it every tenant’s web UI, REST API, and agent connections, by racing two ordinary operations on their own service. The crash is a nil pointer dereference in the service-monitor worker at service/singleton/servicesentinel.go:601. The worker checks a service exists under one lock and later writes to two pointer-valued status maps under a different lock; a concurrent delete removes the entries in the gap. Because the gRPC server has no recovery interceptor, the worker-goroutine panic kills the whole process. Availability only: nothing is read or modified.