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

> An unauthenticated peer can bypass inter-server authentication when no_auth_user is configured, gaining route or leafnode privileges.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 8 Jul 2026
- **Updated:** 9 Jul 2026
- **Also known as:** AZL-92259, BIT-nats-2026-58253, DEBIAN-CVE-2026-58253, GHSA-38x3-76xf-cq45, JLSEC-2026-1153, MINI-587x-32wf-hqhx, MINI-c72m-vmqx-622q, UBUNTU-CVE-2026-58253

## What is CVE-2026-58253?

CVE-2026-58253 is a high-severity authentication bypass vulnerability in nats-io nats-server, published on 8 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-58253?

1 open source package ship an affected version, including nats. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `nats` | Bitnami | All versions | 2.11.16, 2.12.6 |

Products: Linuxfoundation Nats-Server.

## How do I fix CVE-2026-58253?

Upgrade nats to a fixed version for your release line: 2.11.16 or 2.12.6.

## Is CVE-2026-58253 being exploited?

There is no known exploitation of CVE-2026-58253 in the wild and no public exploit code.

## Other vulnerabilities in nats-io nats-server

- [CVE-2022-28357](https://insights.sbomify.com/CVE-2022-28357/): NATS nats-server allows directory traversal via unintended path to a management action (critical 9.8)
- [CVE-2022-24450](https://insights.sbomify.com/CVE-2022-24450/): Incorrect Authorization in NATS nats-server (high 8.8)
- [CVE-2026-33216](https://insights.sbomify.com/CVE-2026-33216/): NATS has MQTT plaintext password disclosure (high 8.6)
- [CVE-2026-58207](https://insights.sbomify.com/CVE-2026-58207/): NATS Server: Remote crash via integer overflow in Connz pagination (high 7.7)
- [CVE-2026-58210](https://insights.sbomify.com/CVE-2026-58210/): NATS Server: MQTT partial CONNECT packets can exhaust pre-auth memory (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-58253 and fix it if it is affected.

What it is: CVE-2026-58253 is a high-severity authentication bypass vulnerability in nats-io nats-server, published on 8 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-58253 in the wild and no public exploit code.

Affected packages and fixed versions:
- nats (Bitnami): affected all versions; fixed in 2.11.16, 2.12.6

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-58253/ (Markdown: https://insights.sbomify.com/CVE-2026-58253/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-58253
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-58253
- OSV: https://osv.dev/vulnerability/CVE-2026-58253

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-58253/
Summaries are generated and may contain mistakes; the official description above is the record.