Uncaught Exception in nats-server - CVE-2026-58208
Published: June 30, 2026
Vulnerability identifier: #VU135928
CSH Severity: Medium
CVSS v4: 8.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-58208
CWE-ID: CWE-248
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to an uncaught exception in the WebSocket listener MQTT-over-WebSocket path when handling requests for the MQTT-over-WebSocket path while MQTT is not configured. A remote attacker can send a specially crafted request to cause a denial of service.
Only deployments that enable WebSocket while leaving MQTT disabled are affected.
Affected software
nats-server
How to mitigate CVE-2026-58208
Install security update from vendor's website.
nats-server - addressed in versions 2.12.12, 2.14.3