vulntracker.iovulntracker.io
© 2026 vulntracker.io

CVE-2026-58208

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

HIGH
7.5
CVSS Score
Published: July 8, 2026 at 08:17 PM UTC
Updated: October 25, 2026 at 05:10 PM UTC
2 products affected across 2 vendorsNats ServerNats Server

Using nats-server by nats-io?

Get instant alerts when new vulnerabilities affect nats-server - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Start FreeSign In
Severity
HIGH7.5
Exploit prediction
EPSS 0.6%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Nats Server· Linuxfoundation
95%
2.12.0 ≤ v < 2.12.122.14.0 ≤ v < 2.14.3
Affected range stops below 2.12.12, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.14.3, so it looks safe — our inference, not a vendor statement
Nats Server· Nats Io
90%
v < 2.12.12
Affected range stops below 2.12.12, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.14.3, so it looks safe — our inference, not a vendor statement

References (5)

x_refsource_CONFIRMMitigationVendor Advisory
Source: cverecord
https://github.com/nats-io/nats-server/security/advisories/GHSA-p957-7v2w-g93g
x_refsource_MISCPatch
Source: cverecord
https://github.com/nats-io/nats-server/commit/73b3dd9a5ea0fa7bf08b702338676355b29b5fb4
x_refsource_MISCPatch
Source: cverecord
https://github.com/nats-io/nats-server/commit/837536b98b3a9280b993282155ff2bdd3ca38c30
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/nats-io/nats-server/releases/tag/v2.12.12
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/nats-io/nats-server/releases/tag/v2.14.3

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGH[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-248

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Create accountSign in
Free plan, no card