CVE-2026-58211CWE-863

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

Medium · published July 8, 2026

CVSS v3.1
5.4
EPSS
0%
Percentile
20.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00292 · 20.7th percentile
Weakness
CWE-863 · Incorrect Authorization
Published
2026-07-08T20:16Z
EPSS history
Timeline
  • 08 JUL 20:16Z
    NATS Server: `no_auth_user` pre-CONNECT fast path bypasses user connection restrictions
    cvelistv5