CVE-2026-58253 Details
Description
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, when no_auth_user was configured, a parser fast path intended for ordinary client connections could also apply to route or leafnode listeners, allowing an unauthenticated peer to bypass inter-server CONNECT authentication and operate with the privileges associated with that connection type. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.
An authentication bypass vulnerability has been identified in NATS Server versions through 2.12.6, 2.11.15 and prior to 2.14.0. When 'no_auth_user' was enabled, a fast path in the parser meant for regular client connections could inadvertently be applied to route or leafnode listeners. This flaw allowed an unauthenticated peer to bypass the inter-server CONNECT authentication, exploiting the privileges of the connection type. The vulnerability arises from the 'no_auth_user' feature, which, when combined with certain listener types, can create a gap in the expected authentication flow.
Users can upgrade to NATS Server versions 2.14.0, 2.12.7, or 2.11.16 to address this vulnerability. Instructions for downloading these versions are available on the NATS Server GitHub releases page.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 9, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-287 | Improper Authentication | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| linuxfoundation nats-server | < 2.11.16 >= 2.12.0, < 2.12.7 |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 13, 2026 | Initial Analysis | [email protected] |
| Jul 9, 2026 | CVE Modified | CISA-ADP |
| Jul 8, 2026 | New CVE Received | [email protected] |