High severity · published Mar 25, 2026
CVE-2026-33218
NATS has pre-auth server panic via leafnode handling
7.5
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 50% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NA
nats-server · nats-io
< < 2.11.15; >= 2.12.0-RC.1, < 2.12.6 · source: vendor, NVD
MG
Multicluster Global Hub 1.4.5 · Red Hat
All versions, or not specified · source: CISA
MG
Multicluster Global Hub 1.6.5 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat multicluster global hub 1.5.3 · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33218
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33218
Mitigation
https://advisories.nats.io/CVE/secnote-2026-10.txt
Mitigation
https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:21769
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:22347
access.redhat.com
https://access.redhat.com/errata/RHSA-2026:23345
access.redhat.com
https://access.redhat.com/security/cve/CVE-2026-33218
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