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CVE-2026-33246

MEDIUM CVSS 3.1: 5.4 EPSS 0.02%
Updated Mar 26, 2026
Linuxfoundation
Parameter Value
CVSS 5.4 (MEDIUM)
Affected Versions 2.12.0 — 2.12.6
Fixed In 2.11.15
Type CWE-287 (Improper Authentication), CWE-290
Vendor Linuxfoundation
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
Low
Partial data leak
Integrity
Low
Partial data modification
Availability
None
No disruption

CVSS Vector v3.1

Vulnerable Products 2

Configuration From (including) Up to (excluding)
Linuxfoundation Nats-Server
cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*
2.11.15
Linuxfoundation Nats-Server
cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*
2.12.0 2.12.6