nats-io/nats-server · Security
NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers
- GHSA ID
- GHSA-55h8-8g96-x4hj
- CVE ID
- CVE-2026-33246
- Severity
- medium
- Published
- Updated
- CVSS
- 6.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
- CVSS v3
- 6.4 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
Description
Background
NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing.
The nats-server allows hub/spoke topologies using "leafnode" connections by other nats-servers. NATS messages can have headers.
Problem Description
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.
Thus NATS clients relying upon the Nats-Request-Info: header could be spoofed.
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.
Affected Versions
Any version before v2.12.6 or v2.11.15
Workarounds
None.
CWEs
- CWE-287 · Improper Authentication
- CWE-290 · Authentication Bypass by Spoofing