What is CVE-2026-33217?

CVE-2026-33217 is a high-severity vulnerability in Nats-io Nats-server, classified under Incorrect Authorization. CVSS score: 7.1/10. Published 2026-03-25.

How severe is CVE-2026-33217?

High severity. CVSS v3 base score is 7.1 out of 10.

Auth bypass in Nats-io Nats-server

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, when using ACLs on message subjects, these ACLs were not applied in the `$MQTT.>` namespace, allowing MQT…

Vulnerability class: Broken Access Control

EPSS: 0.000 (11.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N.

Affected products

Nats-io Nats-server — versions < 2.11.15, >= 2.12.0-RC.1, < 2.12.6

Weakness classification (CWE)

CWE-863 — Incorrect Authorization

References

https://github.com/nats-io/nats-server/security/advisories/GHSA-jxxm-27vp-c3m5 (x_refsource_CONFIRM)
https://advisories.nats.io/CVE/secnote-2026-07.txt (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-33217?: CVE-2026-33217 is a high-severity vulnerability in Nats-io Nats-server, classified under Incorrect Authorization. CVSS score: 7.1/10. Published 2026-03-25.
How severe is CVE-2026-33217?: High severity. CVSS v3 base score is 7.1 out of 10.