---
id: CVE-2026-58214
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 2.14.3 and 2.12.12, an authenticated MQTT
  client could subscribe to the internal $MQTT.deliver.pubrel subject family,
  bypassing co…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-863
vendor: linuxfoundation
product: nats-server
affected:
  - nats-server < 2.12.12
  - 'nats-server >= 2.14.0, < 2.14.3'
patched:
  - nats-server 2.14.3
published: '2026-07-08'
updated: '2026-07-13'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-58214'
references:
  - url: >-
      https://github.com/nats-io/nats-server/commit/297b166be60fe13144084eed4b25201ead03204a
    label: security-advisories@github.com
  - url: >-
      https://github.com/nats-io/nats-server/commit/34b09657bb596d5f850eaa5cfc97ea6b2f989a97
    label: security-advisories@github.com
  - url: 'https://github.com/nats-io/nats-server/releases/tag/v2.12.12'
    label: security-advisories@github.com
  - url: 'https://github.com/nats-io/nats-server/releases/tag/v2.14.3'
    label: security-advisories@github.com
  - url: >-
      https://github.com/nats-io/nats-server/security/advisories/GHSA-4g68-3pwx-5vfj
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00349
epssPercentile: 0.25793
ingestedAt: '2026-07-13T15:27:34.246Z'
---

## Overview

NATS 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 authenticated MQTT client could subscribe to the internal $MQTT.deliver.pubrel subject family, bypassing configured subscribe permissions and exposing MQTT QoS2 protocol metadata for sessions in the account. This issue is fixed in versions 2.14.3 and 2.12.12.

## Affected

- `nats-server < 2.12.12`
- `nats-server >= 2.14.0, < 2.14.3`

## Remediation

Upgrade past the affected range:

- `nats-server 2.14.3`