Read the docs
TI-2026-25664 Aliases CVE-2026-33246GHSA-55h8-8g96-x4hj

NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers

Priority LOW 27CWE-287Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
None
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
Low · Low · None
Fix status
Partial Red Hat: 2 without a fix

Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-287.

Summary

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a `Nats-Request-Info:` message header, providing information about a request. This is supposed to provide enough information to allow for account/user identification, such that NATS clients could make their own decisions on how to trust a message, provided that they trust the nats-server as a broker. A leafnode connecting to a nats-server is not fully trusted unless the system account is bridged too. Thus identity claims should not have propagated unchecked. Prior to versions 2.11.15 and 2.12.6, NATS clients relying upon the Nats-Request-Info: header could be spoofed. This does not directly affect the nats-server itself, but the CVSS Confidentiality and Integrity scores are based upon what a hypothetical client might choose to do with this NATS header. Versions 2.11.15 and 2.12.6 contain a fix. No known workarounds are available.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00149 4th percentileScored 2026-11-07
Fix Partial nats-server (nats-io): 2.11.15, 2.12.6github.com/nats-io/nats-server/v2 (Go): 2.11.15, 2.12.6Red Hat: 2 without a fix

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 2.11.15; 2.12.0-RC.1 to before 2.12.62.11.15, 2.12.6Patch availableCNA
—github.com/nats-io/nats-server/v2 (Go)before 2.11.152.11.15Patch availableGHSA-55h8-8g96-x4hj
—github.com/nats-io/nats-server/v2 (Go)2.12.0-RC.1 to before 2.12.62.12.6Patch availableGHSA-55h8-8g96-x4hj
—github.com/nats-io/nats-server (Go)all versions—No fix listedGHSA-55h8-8g96-x4hj
  • nats-server Vendorbackstage Affected before 2.11.15; 2.12.0-RC.1 to before 2.12.6 Fixed in 2.11.15, 2.12.6 Patch available CNA
  • github.com/nats-io/nats-server/v2 (Go) Vendor— Affected before 2.11.15 Fixed in 2.11.15 Patch available GHSA-55h8-8g96-x4hj
  • github.com/nats-io/nats-server/v2 (Go) Vendor— Affected 2.12.0-RC.1 to before 2.12.6 Fixed in 2.12.6 Patch available GHSA-55h8-8g96-x4hj
  • github.com/nats-io/nats-server (Go) Vendor— Affected all versions Fixed in — No fix listed GHSA-55h8-8g96-x4hj

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*before 2.11.15; 2.12.0 to before 2.12.6Vulnerablebackstage
  • cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:* Versions before 2.11.15; 2.12.0 to before 2.12.6 Vulnerable ·backstage

Remediation

  • Fix · CNA nats-server (nats-io) Fixed in 2.11.15, 2.12.6
  • Fix · GHSA-55h8-8g96-x4hj github.com/nats-io/nats-server/v2 (Go) Fixed in 2.11.15 Advisory →
  • Fix · GHSA-55h8-8g96-x4hj github.com/nats-io/nats-server/v2 (Go) Fixed in 2.12.6 Advisory →

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Multicluster Global HubAffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 4AffectedNo fix yet: Fix deferred

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33246
  2. 2026-10-03 Alias added: GHSA-55h8-8g96-x4hj

References

Advisory 3

Other 1

  • 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