CVE-2026-33218

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 v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://advisories.nats.io/CVE/secnote-2026-10.txt	Mitigation Vendor Advisory
https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339	Mitigation Vendor Advisory
https://access.redhat.com/errata/RHSA-2026:21769
https://access.redhat.com/errata/RHSA-2026:22347
https://access.redhat.com/errata/RHSA-2026:23345
https://access.redhat.com/security/cve/CVE-2026-33218
https://bugzilla.redhat.com/show_bug.cgi?id=2451450
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33218.json

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:linuxfoundation:nats-server::::::::
	cpe:2.3:a:linuxfoundation:nats-server::::::::

History

No history.

Information

Published : 2026-03-25 20:16

Updated : 2026-09-09 13:19

NVD link : CVE-2026-33218

Mitre link : CVE-2026-33218

CVE.ORG link : CVE-2026-33218

JSON object : View

Products Affected

linuxfoundation

nats-server

CWE

CWE-20

Improper Input Validation

CWE-1286

Improper Validation of Syntactic Correctness of Input

{"id": "CVE-2026-33218", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-33218", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "yes"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-03-26T15:37:53.583818Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}, {"type": "Secondary", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.5, "attackVector": "NETWORK", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 3.9}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "nats-io", "product": "nats-server", "versions": [{"status": "affected", "version": "< < 2.11.15"}, {"status": "affected", "version": ">= 2.12.0-RC.1, < 2.12.6"}]}]}, {"source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "affectedData": [{"cpes": ["cpe:/a:redhat:multicluster_globalhub:1.4::el9"], "vendor": "Red Hat", "product": "Multicluster Global Hub 1.4.5", "versions": [{"status": "unaffected", "version": "1779579439", "lessThan": "*", "versionType": "rpm"}], "packageName": "multicluster-globalhub/multicluster-globalhub-grafana-rhel9", "collectionURL": "https://catalog.redhat.com/software/containers/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:multicluster_globalhub:1.6::el9"], "vendor": "Red Hat", "product": "Multicluster Global Hub 1.6.5", "versions": [{"status": "unaffected", "version": "1780167118", "lessThan": "*", "versionType": "rpm"}], "packageName": "multicluster-globalhub/multicluster-globalhub-grafana-rhel9", "collectionURL": "https://catalog.redhat.com/software/containers/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:multicluster_globalhub:1.5::el9"], "vendor": "Red Hat", "product": "Red Hat multicluster global hub 1.5.3", "versions": [{"status": "unaffected", "version": "1778867753", "lessThan": "*", "versionType": "rpm"}], "packageName": "multicluster-globalhub/multicluster-globalhub-grafana-rhel9", "collectionURL": "https://catalog.redhat.com/software/containers/", "defaultStatus": "affected"}, {"cpes": ["cpe:/a:redhat:openshift:4"], "vendor": "Red Hat", "product": "Red Hat OpenShift Container Platform 4", "packageName": "openshift4/oc-mirror-plugin-rhel9", "collectionURL": "https://access.redhat.com/downloads/content/package-browser/", "defaultStatus": "unaffected"}]}], "published": "2026-03-25T20:16:32.623", "references": [{"url": "https://advisories.nats.io/CVE/secnote-2026-10.txt", "tags": ["Mitigation", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339", "tags": ["Mitigation", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://access.redhat.com/errata/RHSA-2026:21769", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}, {"url": "https://access.redhat.com/errata/RHSA-2026:22347", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}, {"url": "https://access.redhat.com/errata/RHSA-2026:23345", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}, {"url": "https://access.redhat.com/security/cve/CVE-2026-33218", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2451450", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}, {"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33218.json", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-20"}]}, {"type": "Secondary", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "description": [{"lang": "en", "value": "CWE-1286"}]}], "descriptions": [{"lang": "en", "value": "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."}, {"lang": "es", "value": "NATS-Server es un servidor de alto rendimiento para NATS.io, un sistema de mensajer\u00eda nativo de la nube y del borde. Antes de las versiones 2.11.15 y 2.12.6, un cliente que puede conectarse al puerto leafnode puede bloquear el nats-server con un mensaje malformado espec\u00edfico pre-autenticaci\u00f3n. Las versiones 2.11.15 y 2.12.6 contienen una correcci\u00f3n. Como soluci\u00f3n alternativa, deshabilite el soporte de leafnode si no es necesario o restrinja las conexiones de red al puerto leafnode, si es factible sin comprometer el servicio ofrecido."}], "lastModified": "2026-09-09T13:19:23.977", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "13EA156E-2759-4586-A22E-CDEAAD4D610C", "versionEndExcluding": "2.11.15"}, {"criteria": "cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4E347CFB-C56D-4FD8-8DD8-3D34C08D7154", "versionEndExcluding": "2.12.6", "versionStartIncluding": "2.12.0"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}