GHSA-v722-jcv5-w7mc — high GitHub Advisory (CVE-2026-33216) in go/github.com/nats-io/nats-server/v2

Description

Background

NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing.

The nats-server provides an MQTT client interface.

Problem Description

For MQTT deployments using usercodes/passwords: MQTT passwords are incorrectly classified as a non-authenticating identity statement (JWT) and exposed via monitoring endpoints.

Affected Versions

Any version before v2.12.6 or v2.11.15

Workarounds

Ensure monitoring end-points are adequately secured.

Best practice remains to not expose the monitoring endpoint to the Internet or other untrusted network users.

Basic information

Type: reviewed
Severity: high
Advisory on GitHub: Open advisory ↗
Repository advisory: Open repository advisory ↗
Source code: Browse source ↗
Published (advisory): 2026-03-24 21:42:10 UTC
Updated: 2026-03-27 22:09:29 UTC
GitHub reviewed: 2026-03-24 21:42:10 UTC
NVD published: 2026-03-25

Score	Percentile
0.04%	13.37%

CVSS Scores

Base score	Version	Severity	Vector
8.6	3.1	—	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:N) Service keeps running; no real outage angle.

Identifiers

Type	Value
GHSA	GHSA-v722-jcv5-w7mc ↗
CVE	CVE-2026-33216 ↗

CWEs

CWE id	Name
CWE-256	Plaintext Storage of a Password

Affected packages (3)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
go	github.com/nats-io/nats-server/v2	< 2.11.15	2.11.15	—
go	github.com/nats-io/nats-server/v2	>= 2.12.0-RC.1, < 2.12.6	2.12.6	—
go	github.com/nats-io/nats-server	> 0	—	—

NATS has MQTT plaintext password disclosure