Home/CVE/NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a
CVE

CVE-2026-33246

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. The nats-server offers a

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.

MEDIUM · CVSS 6.4 EPSS 0.00034
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-287Improper Authentication
CWE-290Authentication Bypass by Spoofing
▤

Affected Products & Versions

2
linuxfoundation nats-server< 2.11.15
linuxfoundation nats-server>= 2.12.0 and < 2.12.6
▤

Affected Packages

2
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Go github.com/nats-io/nats-server MODERATE
Go github.com/nats-io/nats-server/v2 MODERATE fixed in 2.11.15
▣

Scoring & Timeline

6.4
MEDIUM · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD25 Mar 2026 · 08:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
no
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://advisories.nats.io/CVE/secnote-2026-08.txtVendor Advisory
https://github.com/nats-io/nats-server/security/advisories/GHSA-55h8-8g96-x4hjVendor Advisory
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