CVE-2026-33246

Description

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.

How to fix CVE-2026-33246

To remediate CVE-2026-33246, upgrade the affected package to a fixed version below.

• —upgrade to 2.11.15 or later
• —no fix listed
• —no fix listed
• —no fix listed
• —upgrade to 2.11.15 or later
• —upgrade to 2.11.15 or later

Is CVE-2026-33246 being exploited?

Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.

Affected packages (6)

• from 0, < 2.11.15, >= 2.12.0, < 2.12.6
• from 0
• from 0
• from 0
• from 0, < 2.11.15
• from 0, < 2.11.15, >= 2.12.0-RC.1, < 2.12.6

CVSS scores

References (5)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-33246
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-33246
• PATCHgithub.com/nats-io/nats-server
• WEBadvisories.nats.io/CVE/secnote-2026-08.txt
• WEB