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Vulnerability record · CVE-2026-33223 · published 25 March 2026

CVE-2026-33223: Linuxfoundation nats-server authentication bypass by spoofing 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, the NATS message header `Nats-Request-Info:` is supposed to be a guarantee of identity by the NATS server, but the stripping of this header from inbound messages was not fully effective. An attacker with valid credentials for any regular client interface could thus spoof their identity to services which rely upon this header. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

5.4 CVSS 3.1 Medium EPSS 0.24% · top 86.5% CWE-290 · Authentication bypass by spoofing
5.4CVSS 3.1 base score
0.24%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 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, the NATS message header `Nats-Request-Info:` is supposed to be a guarantee of identity by the NATS server, but the stripping of this header from inbound messages was not fully effective. An attacker with valid credentials for any regular client interface could thus spoof their identity to services which rely upon this header. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

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

Affected products

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

References

LinkTags
https://advisories.nats.io/CVE/secnote-2026-09.txt Vendor Advisory
https://github.com/nats-io/nats-server/security/advisories/GHSA-pwx7-fx9r-hr4h Vendor Advisory

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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-2026-33223), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.