Review reviewHigh

CVE-2026-33218

nats-io nats-server, Multicluster Global Hub 1.5.4, Red Hat multicluster global hub 1.4.4

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.

CVSS: 7.5
EPSS: 0.62%
CISA KEV: Not listed
Published: 2026.03.26

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.62%

Technical severityCVSS 7.5

Vulnerability overview

Affected product and versions

Product: nats-io nats-server, Multicluster Global Hub 1.5.4, Red Hat multicluster global hub 1.4.4
Affected versions: >= < < 2.11.15, >= >= 2.12.0-RC.1, < 2.12.6, < 2.11.15, >= 2.12.0 < 2.12.6
Fixed versions: 2.11.15, 2.12.6

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that nats-io nats-server, Multicluster Global Hub 1.5.4, Red Hat multicluster global hub 1.4.4 and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE: CWE-1286, CWE-20