UBUNTU-CVE-2026-58211
NATS Server versions prior to 2.14.3 and 2.12.12 contain a vulnerability where a client can be registered as the configured no_auth_user via a parser path triggered when the first client operation is not CONNECT. This bypasses user-level connection restrictions such as allowed_connection_types or proxy_required that would normally apply with authentication. The issue is fixed in versions 2.14.3 and 2.12.12. Several Ubuntu package versions are affected.
AI Analysis
Technical Summary
The vulnerability in NATS Server allows an unauthenticated client to bypass user-level connection restrictions by exploiting a parser path when the initial client operation is not CONNECT. This enables the client to be registered as the no_auth_user, circumventing restrictions like allowed_connection_types and proxy_required. The flaw affects versions prior to 2.14.3 and 2.12.12 and has been addressed in these fixed versions. The affected Ubuntu package versions include multiple 2.9 and 2.10 releases as listed.
Potential Impact
An attacker can bypass user-level connection restrictions that normally require authentication, potentially allowing unauthorized access with limited privileges assigned to the no_auth_user. This could lead to unauthorized connection types or proxy bypass but does not impact confidentiality or availability beyond limited information disclosure and integrity impact as per the CVSS vector.
Mitigation Recommendations
Upgrade affected NATS Server installations to version 2.14.3 or 2.12.12 or later, where this vulnerability is fixed. Since this is not a cloud service, manual patching is required. No other mitigation or temporary workaround is indicated.
UBUNTU-CVE-2026-58211
Description
NATS Server versions prior to 2.14.3 and 2.12.12 contain a vulnerability where a client can be registered as the configured no_auth_user via a parser path triggered when the first client operation is not CONNECT. This bypasses user-level connection restrictions such as allowed_connection_types or proxy_required that would normally apply with authentication. The issue is fixed in versions 2.14.3 and 2.12.12. Several Ubuntu package versions are affected.
CVSS v3.1
Score 5.4medium
Affected software
pkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]~esm1?arch=source&distro=esm-apps/resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in NATS Server allows an unauthenticated client to bypass user-level connection restrictions by exploiting a parser path when the initial client operation is not CONNECT. This enables the client to be registered as the no_auth_user, circumventing restrictions like allowed_connection_types and proxy_required. The flaw affects versions prior to 2.14.3 and 2.12.12 and has been addressed in these fixed versions. The affected Ubuntu package versions include multiple 2.9 and 2.10 releases as listed.
Potential Impact
An attacker can bypass user-level connection restrictions that normally require authentication, potentially allowing unauthorized access with limited privileges assigned to the no_auth_user. This could lead to unauthorized connection types or proxy bypass but does not impact confidentiality or availability beyond limited information disclosure and integrity impact as per the CVSS vector.
Mitigation Recommendations
Upgrade affected NATS Server installations to version 2.14.3 or 2.12.12 or later, where this vulnerability is fixed. Since this is not a cloud service, manual patching is required. No other mitigation or temporary workaround is indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-58211
- Osv Schema Version
- 1.7.0
- Aliases
- []
- Ecosystems
- ["Ubuntu:24.04:LTS","Ubuntu:25.10","Ubuntu:Pro:26.04:LTS"]
- Database Specific Severity
- null
- Cvss Version
- 3.1
Threat ID: 6a58b46268715ace43d6e729
Added to database: 07/16/2026, 10:37:22 UTC
Last enriched: 07/16/2026, 11:36:46 UTC
Last updated: 07/31/2026, 19:24:49 UTC
Views: 7
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