NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.11.0 and prior to versions 2.11.15 and 2.12.6, a valid client which uses message tracing headers can indicate that the trace messages can be sent to an arbitrary valid subject, including those to which the client does not have publish permission. The payload is a valid trace message and not chosen by the attacker. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to
    versions 2.11.15 and 2.12.6, for MQTT deployments using usercodes/passwords: MQTT passwords are
    incorrectly classified as a non-authenticating identity statement (JWT) and exposed via monitoring
    endpoints. Versions 2.11.14 and 2.12.6 contain a fix. As a workaround, ensure monitoring end-points are
    adequately secured. Best practice remains to not expose the monitoring endpoint to the Internet or other
    untrusted network users. (CVE-2026-33216)

  - NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-
    server provides an MQTT client interface. Prior to versions 2.11.15 and 2.12.5, Sessions and Messages can
    by hijacked via MQTT Client ID malfeasance. Versions 2.11.15 and 2.12.5 patch the issue. No known
    workarounds are available. (CVE-2026-33215)

  - NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to
    versions 2.11.15 and 2.12.6, when using ACLs on message subjects, these ACLs were not applied in the
    `$MQTT.>` namespace, allowing MQTT clients to bypass ACL checks for MQTT subjects. Versions 2.11.15 and
    2.12.6 contain a fix. No known workarounds are available. (CVE-2026-33217)

  - NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to
    versions 2.11.15 and 2.12.6, a client which can connect to the leafnode port can crash the nats-server
    with a certain malformed message pre-authentication. Versions 2.11.15 and 2.12.6 contain a fix. As a
    workaround, disable leafnode support if not needed or restrict network connections to the leafnode port,
    if plausible without compromising the service offered. (CVE-2026-33218)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting     in version 2.11.0 and prior to versions 2.11.15 and 2.12.6, a valid client which uses message tracing     headers can indicate that the trace messages can be sent to an arbitrary valid subject, including those to     which the client does not have publish permission. The payload is a valid trace message and not chosen by     the attacker. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.
    (CVE-2026-33249)

Note that Nessus relies on the presence of the package as reported by the vendor.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting
    in version 2.11.0 and prior to versions 2.11.15 and 2.12.6, a valid client which uses message tracing
    headers can indicate that the trace messages can be sent to an arbitrary valid subject, including those to
    which the client does not have publish permission. The payload is a valid trace message and not chosen by
    the attacker. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.
    (CVE-2026-33249)

ID	Name	Product	Family	Severity
440289	Alpine: nats-server: security update to 2.12.6-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	high
440289	Alpine: nats-server: security update to 2.12.6-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	high
303845	Linux Distros Unpatched Vulnerability : CVE-2026-33249	Nessus	Misc.	medium
439167	SCA: security update for github.com/nats-io/nats-server/v2 (GHSA-8m2x-3m6q-6w8j)	Tenable Cloud Security	SCA Checks	medium
439167	SCA: security update for github.com/nats-io/nats-server/v2 (GHSA-8m2x-3m6q-6w8j)	Tenable Self-Hosted Container Security	SCA Checks	medium

Detections

Analytics

CVE-2026-33249

medium

Tenable Plugins

high

high

medium

medium

medium