CVE-2026-58208: Linuxfoundation Nats-Server

High severity, CVSS 7.5. EPSS: 0.6% chance of exploitation in the next 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.

Affected products

• Linuxfoundation Nats-Server: from 2.12.0, before 2.12.12 (fixed in 2.12.12); from 2.14.0, before 2.14.3 (fixed in 2.14.3)

Published 2026-07-08. Last modified 2026-07-09.