Read the docs
TI-2026-41953 Aliases CVE-2026-58253

NATS Server: Route API Auth Bypass

Priority LOW 38CWE-287Published · Updated

Key facts

Attack vector
Adjacent network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
Low · High · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-287.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00368 30th percentileScored 2026-11-07
Fix Fixed nats-server (nats-io): 2.11.16, 2.12.6

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
backstagenats-serverbefore 2.11.16; 2.12.0-preview.1 to before 2.12.62.11.16, 2.12.6Patch availableCNA
  • nats-server Vendorbackstage Affected before 2.11.16; 2.12.0-preview.1 to before 2.12.6 Fixed in 2.11.16, 2.12.6 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*before 2.11.16; 2.12.0 to before 2.12.7Vulnerablebackstage
  • cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:* Versions before 2.11.16; 2.12.0 to before 2.12.7 Vulnerable ·backstage

Remediation

  • Fix · CNA nats-server (nats-io) Fixed in 2.11.16, 2.12.6

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat Hardened Images

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-58253

References

Patch 3

Advisory 1

Other 3

  • TI-2026-22233 NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead CVSS 3.1HIGH 7.5
  • TI-2022-11116 NATS nats-server 2.2.0 through 2.7.4 allows directory traversal because of an unintended… CVSS 3.1CRITICAL 9.8
  • TI-2020-16319 The JWT library in NATS nats-server before 2.1.9 has Incorrect Access Control because of… CVSS 3.1CRITICAL 9.8
  • TI-2026-25637 NATS has MQTT plaintext password disclosure CVSS 3.1HIGH 8.6
  • TI-2022-08320 NATS nats-server before 2.7.2 has Incorrect Access Control. CVSS 3.1HIGH 8.8
  • TI-2026-41950 NATS Server: Pre-auth server crash via double INFO in leafnode handshake CVSS 3.1HIGH 7.5
See all 35 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences