CVE-2026-33218

highpriority · track · 0EPSS 0.006 · 50 %ileDEEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.63% (50th) EPSS

CVSS 7.5 · high

Is it mine?

14 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · osv · cert_bund

EPSS · scored 2026-10-27

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

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · ENISA EU

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · security-advisories@github.comexploitability 3.9 · impact 3.6

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondaryexploitability 3.9 · impact 3.6

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · OSV

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-1286USCWE-20USCWE-20US

affected products (14)

Products and version ranges known to be affected.

Open Source NATS Server <2.11.15all versionscert_bundDE
Open Source NATS Server <2.12.6all versionscert_bundDE
Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
Open Source NATS Server< 2.11.15cert_bundDE
Open Source NATS Server< 2.12.6cert_bundDE
nats-io nats-server2.12.0-RC.1, → 2.12.6enisa_euvdEU
nats-io nats-server< → 2.11.15enisa_euvdEU
linuxfoundation nats-server< 2.11.15nvdUScpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*
linuxfoundation nats-server2.12.0 → 2.12.6nvdUScpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*
Bitnami nats< 2.11.15osvUSpkg:bitnami/nats
Bitnami nats2.12.0 → 2.12.6osvUSpkg:bitnami/nats
Go github.com/nats-io/nats-serverall versionsosvUSpkg:golang/github.com/nats-io/nats-server
Go github.com/nats-io/nats-server/v2< 2.11.15osvUSpkg:golang/github.com/nats-io/nats-server/v2
Go github.com/nats-io/nats-server/v22.12.0-RC.1 → 2.12.6osvUSpkg:golang/github.com/nats-io/nats-server/v2

advisories (4)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-0858NATS Server: Mehrere SchwachstellenDeutsch2026-03-24csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in NATS Server ausnutzen, um Informationen offenzulegen oder zu manipulieren, einen Denial-of-Service zu verursachen und Sicherheitsmechanismen zu umgehen.
GHSA-vprv-35vv-q339NATS has pre-auth server panic via leafnode handling2026-03-24ghsa · osvUS
### Background NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing. The nats-server allows hub/spoke topologies using "leafnode" connections by other nats-servers. ### Problem Description A client which can connect to the leafnode port can crash the nats-server with a certain malformed message pre-authentication. ### Affected Versions Any version before v2.12.6 or v2.11.15 ### Workarounds 1. Disable leafnode support if not needed. 2. Restrict network connections to your leafnode port, if plausible without compromising the service offered. ### References * This document is canonically: <https://advisories.nats.io/CVE/secnote-2026-10.txt> * GHSA advisory: <https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339> * MITRE CVE entry: <https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-33218>
BIT-nats-2026-33218NATS has pre-auth server panic via leafnode handling2026-03-27vendor · osvUS
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.
GO-2026-4837NATS has pre-auth server panic via leafnode handling in github.com/nats-io/nats-server2026-03-26vendor · osvUS
NATS has pre-auth server panic via leafnode handling in github.com/nats-io/nats-server

also known as (6)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd osv cert_bund nvd NVD CVE.org MITRE

published 2026-03-25modified 2026-09-09

references (14)

External citations — patches, advisories, analysis.

scry

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