CVE-2026-53522: Nezhahq Nezha

Medium severity, CVSS 6.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Nezha Monitoring is a self-hostable, lightweight, servers and websites monitoring and O&M tool. From version 1.0.0 to before version 2.2.0, the Nezha dashboard exposes two endpoints that create long-lived WebSocket streams to monitored agents: POST /api/v1/terminal → createTerminal() (terminal.go:27-67) and POST /api/v1/file → createFM() (fm.go:28-67). Both call rpc.NezhaHandlerSingleton.CreateStream(streamId, ...) which inserts a new ioStreamContext into an unbounded map[string]*ioStreamContext (s.ioStreams in io_stream.go:59-67). There is no per-user rate limit, no global semaphore, and no per-server connection cap. This issue has been patched in version 2.2.0.

Affected products

• Nezhahq Nezha: from 1.0.0, before 2.2.0 (fixed in 2.2.0)

Published 2026-06-12. Last modified 2026-06-17.