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CVE-2026-33216— NATS has MQTT plaintext password disclosure

Quick assessment

Affected
nats-io nats-server
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Nats-Server是Nats开源的一个用于 Nats.io、云和边缘本机消息传递系统的高性能服务器。 Nats-Server 2.11.15之前版本和2.12.6之前版本存在安全漏洞，该漏洞源于MQTT密码被错误分类并暴露于监控端点，可能导致信息泄露。

CVSS 8.6 · High EPSS 0.63% · P49

Possible ATT&CK Techniques 1 AI

T1530 · Data from Cloud Storage

Affected Version Matrix 2

VendorProduct Version RangeStatus
nats-io nats-server < 2.11.15 affected
>= 2.12.0-RC.1, < 2.12.6 affected
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I. Basic Information for CVE-2026-33216

Vulnerability Information
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Vulnerability Title
NATS has MQTT plaintext password disclosure
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
明文存储口令
Source: CVE Program / CVE List V5
Vulnerability Title
Nats-Server 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Nats-Server是Nats开源的一个用于 Nats.io、云和边缘本机消息传递系统的高性能服务器。 Nats-Server 2.11.15之前版本和2.12.6之前版本存在安全漏洞，该漏洞源于MQTT密码被错误分类并暴露于监控端点，可能导致信息泄露。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
nats-io nats-server < 2.11.15 -

II. Public POCs for CVE-2026-33216

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III. Intelligence Information for CVE-2026-33216

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Patches & Fixes for CVE-2026-33216 (1)

Vendor Advisories for CVE-2026-33216 (1)

Same Patch Batch · nats-io · 2026-03-25 · 12 CVEs total

CVE-2026-27889 7.5 HIGH NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead
CVE-2026-29785 7.5 HIGH NATS Server panic via malicious compression on leafnode port
CVE-2026-33218 7.5 HIGH NATS has pre-auth server panic via leafnode handling
CVE-2026-33247 7.4 HIGH NATS credentials are exposed in monitoring port via command-line argv
CVE-2026-33217 7.1 HIGH NATS allows MQTT clients to bypass ACL checks
CVE-2026-33246 6.4 MEDIUM NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers
CVE-2026-33223 6.4 MEDIUM NATS Server: Incomplete Stripping of Nats-Request-Info Header Allows Identity Spoofing
CVE-2026-33219 5.3 MEDIUM NATS is vulnerable to pre-auth DoS through WebSockets client service
CVE-2026-33222 4.9 MEDIUM NATS JetStream has an authorization bypass through its Management API
CVE-2026-33249 4.3 MEDIUM NATS: Message tracing can be redirected to arbitrary subject
CVE-2026-33248 4.2 MEDIUM NATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching

IV. Related Vulnerabilities

Same product: nats-server
Same vendor: nats-io
Same weakness: CWE-256

V. Comments for CVE-2026-33216

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