Medium6.8Red Hat Linux

Medium [CVE-2026-58208] Denial of Service due to incorrect MQTT-over-WebSocket request routing

This medium-severity Red Hat Linux advisory covers CVE-2026-58208.

CVE-2026-58208 Published Jul 8, 2026Updated by vendor Jul 8, 2026

CVE-2026-58208

Affected products & platforms

Red Hat LinuxUnclassified

Open vendor advisory

Android app · Google Play

Monitor future Red Hat Linux CVEs from your phone.

Choose a whole vendor or a precise platform, then receive matching security advisories by phone notification, email, or both. Coverage follows 32 official vendor sources and 160+ reviewed platform categories.

Matching phone alertsOptional email delivery

Get CVE alerts See app features

Summary

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.

A flaw was found in NATS Server. This can result in a Denial of Service (DoS) for the NATS Server.

This Moderate flaw in NATS Server allows an unauthenticated remote attacker to cause a denial of service. This impacts the availability of NATS Server deployments that expose a WebSocket listener, as it does not require specific MQTT configuration to exploit.

Red Hat severity: Moderate — CVSS 6.8 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H). Weakness: CWE-824.

Red Hat lists Red Hat Hardened Images as not affected.

Affected versions

< 2.14.3
< 2.12.12

Official advisory · high-confidence parse· fetched 10 days ago·verify at source

Fixed versions

2.14.3
2.12.12

Official advisory · high-confidence parse· fetched 10 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation

To mitigate this issue, restrict network access to the NATS Server's WebSocket listener to trusted clients only using firewall rules. If the WebSocket listener is not required, it can be disabled in the NATS Server configuration. Disabling the WebSocket listener may impact services that rely on WebSocket connectivity to the NATS Server. After making configuration changes, ensure to restart the NATS Server process for the changes to take effect.

Official advisory · high-confidence parse· fetched 10 days ago·verify at source

Discussion(0)

No comments yet. Share field notes, upgrade gotchas, or questions — verify against the vendor advisory before acting on community advice.