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Vulnerability · Published Mar 25, 2026 · Assigned by GitHub_M

CVE-2026-33216NATS has MQTT plaintext password disclosure

High 8.6

In plain English

A high-severity security flaw in nats-server from nats-io. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.6High
Exploit odds (30 days)0.4%top 68.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.23nats-server2.12.6-r0ALPINE-CVE-2026-33216
Alpine:v3.24nats-server2.12.6-r0ALPINE-CVE-2026-33216
Debian:12nats-serverno fix listedDEBIAN-CVE-2026-33216
Debian:13nats-serverno fix listedDEBIAN-CVE-2026-33216
Debian:14nats-server2.12.6-1DEBIAN-CVE-2026-33216
Gogithub.com/nats-io/nats-serverno fix listedGHSA-v722-jcv5-w7mc
Gogithub.com/nats-io/nats-serverno fix listedGO-2026-4836
Gogithub.com/nats-io/nats-server/v22.11.15, 2.12.6GO-2026-4836
Gogithub.com/nats-io/nats-server/v22.11.15GHSA-v722-jcv5-w7mc
Gogithub.com/nats-io/nats-server/v22.12.6GHSA-v722-jcv5-w7mc
Ubuntu:24.04:LTSnats-serverno fix listedUBUNTU-CVE-2026-33216
Ubuntu:25.10nats-serverno fix listedUBUNTU-CVE-2026-33216
Ubuntu:26.10nats-serverno fix listedUBUNTU-CVE-2026-33216

Affected products (as reported)

VendorProductVersions
nats-io nats-server < 2.11.15>= 2.12.0-RC.1, < 2.12.6

Weakness: CWE-256, CWE-213 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

References