CVE-2026-58211

MEDIUM

NATS Server: `no_auth_user` pre-CONNECT fast path bypasses user connection restrictions

Title source: cna
STIX 2.1

Description

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, a client could be registered as the configured no_auth_user through a parser path used when the first client operation was not CONNECT, bypassing user-level connection restrictions such as allowed_connection_types or proxy_required that normal authentication would apply. This issue is fixed in versions 2.14.3 and 2.12.12.

References (1)

Core 1
Core References

Scores

CVSS v3 5.4
EPSS 0.0029
EPSS Percentile 21.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-863
Status published
Products (3)
linuxfoundation/nats-server 2.12.0 - 2.12.12
nats-io/nats-server < 2.12.12
nats-io/nats-server >= 2.14.0-RC.1, < 2.14.3
Published Jul 08, 2026
Tracked Since Jul 09, 2026