NATS Server: Route API Auth Bypass (CVE-2026-58253)
NATS Server versions prior to 2.14.0, 2.12.7, and 2.11.16 contain an authentication bypass vulnerability affecting route and leafnode listeners when no_auth_user is configured. This flaw allows an unauthenticated peer to bypass inter-server CONNECT authentication and gain privileges associated with that connection type. The issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.
AI Analysis
Technical Summary
NATS Server, a high-performance messaging server, has an authentication bypass vulnerability (CVE-2026-58253) in versions prior to 2.14.0, 2.12.7, and 2.11.16. When the no_auth_user setting is enabled, a parser fast path intended for ordinary client connections also applies to route or leafnode listeners. This allows an unauthenticated peer to bypass inter-server CONNECT authentication and operate with the privileges of that connection type. The vulnerability is resolved in the specified fixed versions.
Potential Impact
An unauthenticated attacker can bypass inter-server authentication mechanisms and gain unauthorized access with the privileges of route or leafnode connections. This could lead to unauthorized message routing or other actions permitted by those connection privileges.
Mitigation Recommendations
A patch is available and the issue is fixed in NATS Server versions 2.14.0, 2.12.7, and 2.11.16. Users should upgrade to one of these versions or later to remediate this vulnerability.
NATS Server: Route API Auth Bypass (CVE-2026-58253)
Description
NATS Server versions prior to 2.14.0, 2.12.7, and 2.11.16 contain an authentication bypass vulnerability affecting route and leafnode listeners when no_auth_user is configured. This flaw allows an unauthenticated peer to bypass inter-server CONNECT authentication and gain privileges associated with that connection type. The issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.
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
NATS Server, a high-performance messaging server, has an authentication bypass vulnerability (CVE-2026-58253) in versions prior to 2.14.0, 2.12.7, and 2.11.16. When the no_auth_user setting is enabled, a parser fast path intended for ordinary client connections also applies to route or leafnode listeners. This allows an unauthenticated peer to bypass inter-server CONNECT authentication and operate with the privileges of that connection type. The vulnerability is resolved in the specified fixed versions.
Potential Impact
An unauthenticated attacker can bypass inter-server authentication mechanisms and gain unauthorized access with the privileges of route or leafnode connections. This could lead to unauthorized message routing or other actions permitted by those connection privileges.
Mitigation Recommendations
A patch is available and the issue is fixed in NATS Server versions 2.14.0, 2.12.7, and 2.11.16. Users should upgrade to one of these versions or later to remediate this vulnerability.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-58253
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:24.04:LTS","Ubuntu:25.10","Ubuntu:Pro:26.04:LTS"]
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a58b45d68715ace43d6be26
Added to database: 07/16/2026, 10:37:17 UTC
Last enriched: 09/08/2026, 15:19:15 UTC
Last updated: 09/14/2026, 22:01:35 UTC
Views: 23
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.