CVE-2026-58211
NATS Server: `no_auth_user` pre-CONNECT fast path bypasses user connection restrictions
CVSS Score
5.4
EPSS Score
0.3%
EPSS Percentile
23th
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.
| CWE | CWE-863 |
| 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:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None
Affected Versions
nats-io / nats-server
< 2.12.12 >= 2.14.0-RC.1, < 2.14.3