CVE-2026-58208
NATS Server: MQTT-over-WebSocket Path Can Crash WebSocket-Only JetStream Servers Before MQTT Is Enabled
CVSS Score
6.8
EPSS Score
0.5%
EPSS Percentile
41th
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.
| CWE | CWE-248 |
| Vendor | nats-io |
| Product | nats-server |
| Published | Jul 8, 2026 |
| Last Updated | Jul 9, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
nats-io / nats-server
>= 2.14.0-RC.1, < 2.14.3 < 2.12.12
References
github.com: https://github.com/nats-io/nats-server/security/advisories/GHSA-p957-7v2w-g93g github.com: https://github.com/nats-io/nats-server/commit/73b3dd9a5ea0fa7bf08b702338676355b29b5fb4 github.com: https://github.com/nats-io/nats-server/commit/837536b98b3a9280b993282155ff2bdd3ca38c30 github.com: https://github.com/nats-io/nats-server/releases/tag/v2.12.12 github.com: https://github.com/nats-io/nats-server/releases/tag/v2.14.3