Nezha Monitoring is a self-hostable, lightweight, servers and websites monitoring and O&M tool. From 2.2.7 until 2.2.11, ServiceSentinel.worker in service/singleton/servicesentinel.go checked an owned service under servicesLock and later dereferenced pointer-valued serviceStatusToday and serviceCurrentStatusData entries under serviceResponseDataStoreLock without revalidating that ServiceSentinel.Delete had not removed them. A RoleMember could concurrently report TCP or ICMP results through the member's own agent and delete the same owned service, causing a nil pointer dereference. Because the gRPC server had no recovery interceptor, the worker panic terminated the whole dashboard process and disrupted every tenant's web interface, REST API, and agent connections. The issue affects availability only and does not disclose or modify data. This issue is fixed in versions 2.2.11 and 2.3.0.

Affected: Go: github.com/nezhahq/nezha

## Summary

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.

## Affected versions

Confirmed in `v2.2.7` through `v2.2.10`. `service/singleton/servicesentinel.go` has the same vulnerable implementation in all four releases. The issue is fixed in `v2.2.11` and later; users should upgrade to the latest release, `v2.3.0`.

## The bug

The worker validates an incoming report and later writes it to two status maps, but the check and the write are guarded by two different locks taken at two different times. Between them, the same member can delete the service and pull the map entries out from under the worker.

The maps hold pointers, so a missing key returns nil and the first field write through it panics:

``` 73: serviceStatusToday map[uint64]*_TodayStatsOfService 74: serviceCurrentStatusData map[uint64]*serviceTaskStatus ```

The worker checks presence via `Get`, which takes `…