# CVE-2026-58253: NATS Server: Route API Auth Bypass

CVE-2026-58253 is fixed in nats-server on 1 platform by DEBIAN-CVE-2026-58253 (version 2.14.1-1), released July 4, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-58253
- Priority: High
- CVSS: 8.8 (Important)
- EPSS: 0.0037
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 8, 2026
- Weakness: Improper Authentication
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58253

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | nats-server Debian 14 | 2.14.1-1 | [DEBIAN-CVE-2026-58253](https://patchblox.com/security/data/fix/linux/debian-cve-2026-58253.md) | Jul 4, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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