6.5

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

Deferred
AliasesGHSA-jg62-j5h6-8mpqGO-2026-5831
Published 12-06-2026Last modified 15-06-2026

Vulnerability summary

CVE-2026-53522 is a medium (CVSS 6.5) vulnerability in nezhahq nezha. EPSS estimates a 0.41% chance of exploitation in the next 30 days, higher than 34.2% of scored vulnerabilities.

Overall risk
26/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.5/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.41%
0%100%
Low · +0.12 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
OPENSUSE-SU-2026:21483-1

Timeline

  1. 12-06-2026
    PublishedVulnerability first disclosed.
  2. 15-06-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.41%

Chance of exploitation in the next 30 days

Percentile

34%

Versus all other CVEs

30-day change

Increase +0.12 pp

From 0.29% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Github.com/nezhahq1 product
  • nezha≥ 1.0.0, < 2.2.0 | ≥ 1.0.0 (No fix recorded)
Nezhahq1 product

2 vendors · 2 products

References

3 links