CVE-2026-33223: NATS Server Incomplete Stripping Of Nats-Request-Info Header Vulnerability
MODERATECVE-2026-33223 is a MODERATE (CVSS 6.4) incomplete stripping of nats-request-info header vulnerability (CWE-290: Authentication Bypass by Spoofing) affecting NATS Server libraries in the Go ecosystem. The issue involves incomplete stripping of nats-request-info header allows identity spoofing. Remediation is available by upgrading affected packages to version 2.11.15, 2.12.6.
CVE-2026-33223 at a Glance
Security Impact
CVSS: 6.4
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N).
How to Fix CVE-2026-33223
To remediate this vulnerability, upgrade all affected NATS Server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade github.com/nats-io/nats-server/v2 to 2.11.15Upgrade github.com/nats-io/nats-server/v2 to 2.12.6Upgrade github.com/nats-io/nats-server to Latest secure releaseRun the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for github.com/nats-io/nats-server/v2How to Check if You Are Affected
To determine whether your application is affected by CVE-2026-33223, inspect your project dependencies for NATS Server:
inspect dependencies for github.com/nats-io/nats-server/v2Analyze the terminal output to locate any version of NATS Server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.11.15), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-290: Authentication Bypass by Spoofing, where this attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks. In NATS Server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2026-33223 Affected NATS Server Versions
3 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
github.com/nats-io/nats-server/v2
|
Go |
< 2.11.15
|
2.11.15
|
|
github.com/nats-io/nats-server/v2
|
Go |
≥ 2.12.0-RC.1
< 2.12.6
|
2.12.6
|
|
github.com/nats-io/nats-server
|
Go |
|
|
References
Frequently Asked Questions
What is CVE-2026-33223?
Which NATS Server versions are affected?
What version fixes CVE-2026-33223?
Is github.com/nats-io/nats-server/v2 affected?
Is github.com/nats-io/nats-server affected?
What is the CVSS score of CVE-2026-33223?
What CWE is associated with CVE-2026-33223?
How can I check Go dependencies for CVE-2026-33223?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-pwx7-fx9r-hr4h",
"modified" : "2026-03-27T22:10:27Z",
"published" : "2026-03-24T21:50:05Z",
"aliases" : [ "CVE-2026-33223" ],
"summary" : "NATS Server: Incomplete Stripping of Nats-Request-Info Header Allows Identity Spoofing",
"details" : "### Background\n\nNATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing.\n\nThe nats-server offers a `Nats-Request-Info:` message header, providing information about a request.\n\n### Problem Description\n\nThe NATS message header `Nats-Request-Info:` is supposed to be a guarantee of identity by the NATS server, but the stripping of this header from inbound messages was not fully effective.\n\nAn attacker with valid credentials for any regular client interface could thus spoof their identity to services which rely upon this header.\n\n### Affected Versions\n\nAny version before v2.12.6 or v2.11.15\n\n### Workarounds\n\nNone.",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/nats-io/nats-server/v2"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "2.11.15"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/nats-io/nats-server/v2"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "2.12.0-RC.1"
}, {
"fixed" : "2.12.6"
} ]
} ]
}, {
"package" : {
"ecosystem" : "Go",
"name" : "github.com/nats-io/nats-server"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/nats-io/nats-server/security/advisories/GHSA-pwx7-fx9r-hr4h"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33223"
}, {
"type" : "WEB",
"url" : "https://advisories.nats.io/CVE/secnote-2026-09.txt"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/nats-io/nats-server"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-290" ],
"severity" : "MODERATE",
"github_reviewed" : true,
"github_reviewed_at" : "2026-03-24T21:50:05Z",
"nvd_published_at" : "2026-03-25T21:16:47Z"
}
}