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Vulnerability record · CVE-2026-33218 · published 25 March 2026

CVE-2026-33218: Linuxfoundation nats-server improper input validation vulnerability

Linuxfoundation · Nats Server

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.

7.5 CVSS 3.1 High EPSS 0.84% · top 43.7% CWE-20 · Improper input validationCWE-1286 · CWE-1286
7.5CVSS 3.1 base score
0.84%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References
9 Sep 2026Last modified by NVD

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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://advisories.nats.io/CVE/secnote-2026-10.txt MitigationVendor Advisory
https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339 MitigationVendor 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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2022-28357Linuxfoundation nats-server path traversal vulnerabilityNATS nats-server 2.2.0 through 2.7.4 allows directory traversal because of an unintended path to a management action from a management account.EPSS 1.2%9.8CVE-2020-26892Linuxfoundation nats-server hard-coded credentials vulnerabilityThe JWT library in NATS nats-server before 2.1.9 has Incorrect Access Control because of how expired credentials are handled.EPSS 2.1%8.8CVE-2026-58253Linuxfoundation nats-server improper authentication vulnerabilityNATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, when no_auth_…EPSS 0.37%8.8CVE-2022-24450Linuxfoundation nats-server missing authorization vulnerabilityNATS nats-server before 2.7.2 has Incorrect Access Control. Any authenticated user can obtain the privileges of the System account by misusing the "d…EPSS 1.3%7.5CVE-2026-58208Linuxfoundation nats-server vulnerabilityNATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a WebSocket listener c…EPSS 0.60%7.5CVE-2026-58250Linuxfoundation nats-server null pointer dereference vulnerabilityNATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.12.8 and 2.11.17, an unauthenticated pee…EPSS 0.74%7.5CVE-2026-58210Linuxfoundation nats-server uncontrolled resource consumption vulnerabilityNATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, an unauthenticated MQT…EPSS 0.74%7.5CVE-2026-33216Linuxfoundation nats-server vulnerabilityNATS-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, for MQTT deploy…EPSS 0.63%

Source: NIST National Vulnerability Database (record CVE-2026-33218), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.