CVE-2026-33218

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, a client which can connect to the leafnode port can crash the nats-server with a certain malformed message pre-authentication. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable leafnode support if not needed or restrict network connections to the leafnode port, if plausible without compromising the service offered.

How to fix CVE-2026-33218

To remediate CVE-2026-33218, upgrade the affected package to a fixed version below.

• —upgrade to 2.11.15 or later
• —no fix listed
• —no fix listed
• —no fix listed
• —upgrade to 2.11.15 or later
• —upgrade to 2.11.15 or later

Is CVE-2026-33218 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (6)

• from 0, < 2.11.15, >= 2.12.0, < 2.12.6
• from 0
• from 0
• from 0
• from 0, < 2.11.15
• from 0, < 2.11.15, >= 2.12.0-RC.1, < 2.12.6

CVSS scores

References (5)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-33218
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-33218
• PATCHgithub.com/nats-io/nats-server
• WEBadvisories.nats.io/CVE/secnote-2026-10.txt
• WEB