CVE-2026-58253

Severity CVSS v4.0:

Pending analysis

Type:

CWE-287 Authentication Issues

Publication date:

08/07/2026

Last modified:

13/07/2026

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.

Impact

Vector 3.x

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L CVSS v3.1 Severity and Metrics:

Base Score: 8.80 HIGH
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L

Attack Vector (AV): Adjacent
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Changed
Confidentiality (C): Low
Integrity (I): High
Availability (A): Low

Base Score 3.x

8.80

Severity 3.x

HIGH

Vulnerable products and versions

CPE	From	Up to
cpe:2.3:a:linuxfoundation:nats-server::::::::		2.11.16 (excluding)
cpe:2.3:a:linuxfoundation:nats-server::::::::	2.12.0 (including)	2.12.7 (excluding)

To consult the complete list of CPE names with products and versions, see this page

CVE-2026-58253

Description

Impact

Vulnerable products and versions

References to Advisories, Solutions, and Tools