CVE-2026-58253

HIGH 8.8

NATS Server: Route API Auth Bypass

CVSS Score

8.8

EPSS Score

0.4%

EPSS Percentile

31th

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.

CWE	CWE-287
Vendor	nats-io
Product	nats-server
Published	Jul 8, 2026
Last Updated	Jul 9, 2026

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CVSS v3 Breakdown

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

Attack Vector

Adjacent

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

High

Availability

Low

Affected Versions

nats-io / nats-server

< 2.11.16 >= 2.12.0-preview.1, < 2.12.6

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/nats-io/nats-server/security/advisories/GHSA-38x3-76xf-cq45 github.com: https://github.com/nats-io/nats-server/commit/7b81dd455ea95960090a84858c7662827948d1b6 github.com: https://github.com/nats-io/nats-server/commit/8b8e1ad4ceed32321e00d4fc6e76be05bc13bca6 github.com: https://github.com/nats-io/nats-server/commit/b86147e81710a52b72a7f7275f91d69f723f5cb3 github.com: https://github.com/nats-io/nats-server/releases/tag/v2.11.16 github.com: https://github.com/nats-io/nats-server/releases/tag/v2.12.7 github.com: https://github.com/nats-io/nats-server/releases/tag/v2.14.0