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

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.

Timeline

1. Mar 25, 2026, 7:50 PM UTCCVE published
2. Mar 28, 2026, 1:39 AM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Mar 28, 2026, 1:42 AM UTCRecord last updated

Affected versions

• nats-io nats-server

  fixed in 2.11.15; From 2.12.0-RC.1 · fixed in 2.12.6

• github.com/nats-io/nats-serverGo

  All versions

• github.com/nats-io/nats-server/v2Go

  fixed in 2.11.15; From 2.12.0-RC.1 · fixed in 2.12.6

• github.com/nats-io/nats-server/v2Go

  fixed in 2.11.15

• github.com/nats-io/nats-server/v2Go

  From 2.12.0-RC.1 · fixed in 2.12.6

References 2