CVE-2026-101088

Summary

Nezha is a server and website monitoring tool. In versions >= 2.2.11 and < 2.3.1, the service sentinel worker (service/singleton/servicesentinel.go) contains an incomplete fix for a previously reported nil dereference denial of service (GHSA-qjpp-gffx-2wm9). The 2026-07-21 fix re-validated the service lifecycle under serviceResponseDataStoreLock but reused an already-captured, now stale reporter pointer and never re-validated the server, and that lock does not guard ServerShared. An authenticated user with the member role who owns an agent can issue a concurrent server delete (POST /api/v1/batch-delete/server) for their own server to win the race window, causing the worker to dereference a missing entry in the server list snapshot. Because the sentinel workers and the gRPC server have no recover()/recovery interceptor, the resulting panic is unrecovered and crashes the entire instance. This is fixed in version 2.3.1.

Affected Software

Weaknesses

• CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition

References

• https://github.com/nezhahq/nezha/security/advisories/GHSA-jx78-55p5-rwv5
• https://www.vulncheck.com/advisories/nezha-before-2.3.1-denial-of-service-via-concurrent-server-delete

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