Vulnerability · Published Jun 12, 2026 · Assigned by GitHub_M

CVE-2026-53522Nezha Monitoring: Unbounded WebSocket Streams — Resource Exhaustion DoS

Medium 6.5

In plain English

A medium-severity resource allocation without limits in nezha from nezhahq. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium

Exploit odds (30 days)0.3%top 71.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/nezhahq/nezha	2.2.0	GHSA-jg62-j5h6-8mpq
Go	github.com/nezhahq/nezha	no fix listed	GO-2026-5831

Affected products (as reported)

Vendor	Product	Versions
nezhahq	nezha	>= 1.0.0, < 2.2.0

Weakness: CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References

https://github.com/nezhahq/nezha/security/advisories/GHSA-jg62-j5h6-8mpq x_refsource_CONFIRM