CVE-2026-33219

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 malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-server before authentication; this requires sending a corresponding amount of data. This is a milder variant of CVE-2026-27571. That earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable websockets if not required for project deployment.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://advisories.nats.io/CVE/secnote-2026-02.txt	Mitigation Vendor Advisory
https://advisories.nats.io/CVE/secnote-2026-11.txt	Mitigation Vendor Advisory
https://github.com/advisories/GHSA-qrvq-68c2-7grw	Mitigation Vendor Advisory
https://github.com/nats-io/nats-server/security/advisories/GHSA-8r68-gvr4-jh7j	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-2026-33219
https://bugzilla.redhat.com/show_bug.cgi?id=2451445
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33219.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-2026-33219

Mitre link : CVE-2026-33219

CVE.ORG link : CVE-2026-33219

JSON object : View

Products Affected

linuxfoundation

nats-server

CWE

CWE-770

Allocation of Resources Without Limits or Throttling

{"id": "CVE-2026-33219", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-33219", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-03-25T20:10:18.603979Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "LOW", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}, "impactScore": 1.4, "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": "2026-03-25T20:16:32.777", "references": [{"url": "https://advisories.nats.io/CVE/secnote-2026-02.txt", "tags": ["Mitigation", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://advisories.nats.io/CVE/secnote-2026-11.txt", "tags": ["Mitigation", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/advisories/GHSA-qrvq-68c2-7grw", "tags": ["Mitigation", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/nats-io/nats-server/security/advisories/GHSA-8r68-gvr4-jh7j", "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-2026-33219", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2451445", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}, {"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33219.json", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-770"}]}, {"type": "Secondary", "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "description": [{"lang": "en", "value": "CWE-770"}]}], "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 malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-server before authentication; this requires sending a corresponding amount of data. This is a milder variant of CVE-2026-27571. That earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable websockets if not required for project deployment."}, {"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 malicioso que puede conectarse al puerto de WebSockets puede causar un uso de memoria ilimitado en el nats-server antes de la autenticaci\u00f3n; esto requiere el env\u00edo de una cantidad de datos correspondiente. Esta es una variante m\u00e1s leve de CVE-2026-27571. Ese problema anterior era una bomba de compresi\u00f3n, esta vulnerabilidad no lo es. Los ataques contra este nuevo problema, por lo tanto, requieren un ancho de banda significativo del cliente. Las versiones 2.11.15 y 2.12.6 contienen una correcci\u00f3n. Como soluci\u00f3n alternativa, deshabilite los websockets si no son necesarios para la implementaci\u00f3n del proyecto."}], "lastModified": "2026-09-09T13:19:24.173", "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"}