CVE-2026-58211: CWE-863: Incorrect Authorization in nats-io nats-server
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.
AI Analysis
Technical Summary
CVE-2026-58211 is an incorrect authorization vulnerability (CWE-863) in nats-io nats-server. Before versions 2.14.3 and 2.12.12, the server's parser path allowed a client to be registered as the no_auth_user if the first client operation was not CONNECT. This bypassed user-level connection restrictions that would normally be enforced by authentication, such as allowed_connection_types and proxy_required. The vulnerability is fixed in versions 2.14.3 and 2.12.12.
Potential Impact
An attacker could bypass user-level connection restrictions by exploiting the parser path that registers clients as no_auth_user without proper authentication. This could lead to unauthorized access with limited privileges, potentially allowing actions normally restricted by connection policies. The confidentiality and integrity impact is low, and availability is not affected.
Mitigation Recommendations
Upgrade nats-server to version 2.14.3 or 2.12.12 or later, where this authorization bypass vulnerability is fixed. No other mitigation or temporary workaround is indicated.
CVE-2026-58211: CWE-863: Incorrect Authorization in nats-io nats-server
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.
CVSS v3.1
Score 5.4medium
Affected software
pkg:github/nats-io/nats-serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-58211 is an incorrect authorization vulnerability (CWE-863) in nats-io nats-server. Before versions 2.14.3 and 2.12.12, the server's parser path allowed a client to be registered as the no_auth_user if the first client operation was not CONNECT. This bypassed user-level connection restrictions that would normally be enforced by authentication, such as allowed_connection_types and proxy_required. The vulnerability is fixed in versions 2.14.3 and 2.12.12.
Potential Impact
An attacker could bypass user-level connection restrictions by exploiting the parser path that registers clients as no_auth_user without proper authentication. This could lead to unauthorized access with limited privileges, potentially allowing actions normally restricted by connection policies. The confidentiality and integrity impact is low, and availability is not affected.
Mitigation Recommendations
Upgrade nats-server to version 2.14.3 or 2.12.12 or later, where this authorization bypass vulnerability is fixed. No other mitigation or temporary workaround is indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-29T17:09:25.872Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a4eb691c9d9e3dbe3b6879e
Added to database: 07/08/2026, 20:44:01 UTC
Last enriched: 07/16/2026, 10:05:38 UTC
Last updated: 08/22/2026, 22:52:15 UTC
Views: 106
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