CVE-2026-101088: Nezha before 2.3.1 Denial of Service via Concurrent Server Delete

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-27 · updated 2026-09-30
Weakness: CWE-367

Description

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 products

nezhahq nezha: from 2.2.11 before 2.3.1 — fixed in 2.3.1

How to fix

Upgrade to a fixed version: nezhahq nezha 2.3.1. Check the vendor advisory for mitigations.

References

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