CVE-2026-58211

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

Published Jul 8, 2026 CVSS 3.1 · 5.4 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Nats
Nats nats Server
Vendors & Products Nats
Nats nats Server
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title NATS Server: `no_auth_user` pre-CONNECT fast path bypasses user connection restrictions
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 5.4, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Jul 9, 2026, 2:27 PM
Reserved
Jun 29, 2026, 5:09 PM
Status
Analyzed
Published
Jul 8, 2026, 9:16 PM
Modified
Oct 25, 2026, 5:10 PM