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.

High

CVSS

8.8

Important

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0037

30th percentile

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

Product	Fixed in	Fix	Released
Linux
nats-server · Debian 14	2.14.1-1	DEBIAN-CVE-2026-58253	Jul 4, 2026

Details

Published
July 8, 2026
Weakness
Improper Authentication
CVSS vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-58253

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