---
id: CVE-2026-58253
title: >-
  NATS Server is a high-performance server for NATS.io, the cloud and edge
  native messaging system
summary: >-
  NATS 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_user was configured, a parser fast path intended for ordinary client
  connections could a…
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L'
cwe:
  - CWE-287
vendor: linuxfoundation
product: nats-server
affected:
  - nats-server < 2.11.16
  - 'nats-server >= 2.12.0, < 2.12.7'
patched:
  - nats-server 2.12.7
published: '2026-07-08'
updated: '2026-07-13'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-58253'
references:
  - url: >-
      https://github.com/nats-io/nats-server/commit/7b81dd455ea95960090a84858c7662827948d1b6
    label: security-advisories@github.com
  - url: >-
      https://github.com/nats-io/nats-server/commit/8b8e1ad4ceed32321e00d4fc6e76be05bc13bca6
    label: security-advisories@github.com
  - url: >-
      https://github.com/nats-io/nats-server/commit/b86147e81710a52b72a7f7275f91d69f723f5cb3
    label: security-advisories@github.com
  - url: 'https://github.com/nats-io/nats-server/releases/tag/v2.11.16'
    label: security-advisories@github.com
  - url: 'https://github.com/nats-io/nats-server/releases/tag/v2.12.7'
    label: security-advisories@github.com
  - url: 'https://github.com/nats-io/nats-server/releases/tag/v2.14.0'
    label: security-advisories@github.com
  - url: >-
      https://github.com/nats-io/nats-server/security/advisories/GHSA-38x3-76xf-cq45
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00368
epssPercentile: 0.30711
ingestedAt: '2026-07-13T15:27:34.317Z'
---

## Overview

NATS 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_user was configured, a parser fast path intended for ordinary client connections could also apply to route or leafnode listeners, allowing an unauthenticated peer to bypass inter-server CONNECT authentication and operate with the privileges associated with that connection type. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.

## Affected

- `nats-server < 2.11.16`
- `nats-server >= 2.12.0, < 2.12.7`

## Remediation

Upgrade past the affected range:

- `nats-server 2.12.7`