CVE-2026-58208Network attack vector

Unauthenticated crash via unchecked MQTT WebSocket upgrade

Published Jul 8, 2026 · Updated Jul 8, 2026

Denial of service in NATS Server before 2.12.12 and 2.14.0-RC.1 through 2.14.2 allows remote attackers to crash the server. The WebSocket wsUpgrade handler accepts the /mqtt path while MQTT is disabled, routing the connection into uninitialized MQTT state that panics. Exploitation requires network access to a WebSocket listener with MQTT disabled; deployments without WebSocket or with MQTT configured are unaffected.

CVSS severity6.8
Medium
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in NATS Server before 2.12.12 and 2.14.0-RC.1 through 2.14.2 allows remote attackers to crash the server. The WebSocket wsUpgrade handler accepts the /mqtt path while MQTT is disabled, routing the connection into uninitialized MQTT state that panics. Exploitation requires network access to a WebSocket listener with MQTT disabled; deployments without WebSocket or with MQTT configured are unaffected.

The record

CVE
CVE-2026-58208
Published
Jul 8, 2026
Updated
Jul 8, 2026
Vendor
NATS
Product
NATS Server
Classifications
CWE-248, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.12.12
  2. Affected versionversion=>= 2.14.0-RC.1, < 2.14.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NATS · NATS Serverversion=< 2.12.12; version=>= 2.14.0-RC.1, < 2.14.3

Published CVSS scores

6.8GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-248Uncaught Exception
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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