What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-03-25 · updated 2026-09-09
• Weakness: CWE-256

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 products

• nats-io nats-server: before 2.11.15; from 2.12.0 before 2.12.6 — fixed in 2.11.15, 2.12.6

How to fix

Upgrade to a fixed version: nats-io nats-server 2.11.15, 2.12.6. Check the vendor advisory for mitigations.

References

• https://advisories.nats.io/CVE/secnote-2026-05.txt
• https://github.com/nats-io/nats-server/commit/b5b63cfc35a57075e09c1f57503d31721bed8099
• https://github.com/nats-io/nats-server/security/advisories/GHSA-v722-jcv5-w7mc
• https://access.redhat.com/errata/RHSA-2026:21769
• https://access.redhat.com/errata/RHSA-2026:22347
• https://access.redhat.com/errata/RHSA-2026:23345
• https://access.redhat.com/security/cve/CVE-2026-33216
• https://bugzilla.redhat.com/show_bug.cgi?id=2451448
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33216.json

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