Medium 6.8Published Jul 8, 2026

CVE-2026-58208NATS Server: MQTT-over-WebSocket Path Can Crash WebSocket-Only JetStream Servers Before MQTT Is Enabled

Updated under an hour ago (Oct 27, 2026, 1:50 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a WebSocket listener could route requests for the MQTT-over-WebSocket path into MQTT handling even when MQTT was not configured, allowing an unauthenticated client with access to the WebSocket listener to reach uninitialized MQTT state and crash the server process. This issue is fixed in versions 2.14.3 and 2.12.12.

CVSS: 6.8 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Weakness (CWE): CWE-248
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Jul 9, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

nats-io nats-server nats_io:nats_server (from the name)	from 2.14.0-RC.1, < 2.14.3; before 2.12.12	CNA record
linuxfoundation nats-server linuxfoundation:nats-server	from 2.12.0 before 2.12.12; from 2.14.0 before 2.14.3	NVD

References

References

https://github.com/nats-io/nats-server/security/advisories/GHSA-p957-7v2w-g93g	x-refsource-confirm, mitigation, vendor-advisory
https://github.com/nats-io/nats-server/commit/73b3dd9a5ea0fa7bf08b702338676355b29b5fb4	x-refsource-misc, patch
https://github.com/nats-io/nats-server/commit/837536b98b3a9280b993282155ff2bdd3ca38c30	x-refsource-misc, patch
https://github.com/nats-io/nats-server/releases/tag/v2.12.12	x-refsource-misc, release-notes
https://github.com/nats-io/nats-server/releases/tag/v2.14.3	x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.