GHSA-55H8-8G96-X4HJ

Vulnerability from github – Published: 2026-03-24 21:50 – Updated: 2026-03-27 22:10
VLAI
Summary
NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers
Details

Background

NATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing.

The nats-server allows hub/spoke topologies using "leafnode" connections by other nats-servers. NATS messages can have headers.

Problem Description

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.

Thus NATS clients relying upon the Nats-Request-Info: header could be spoofed.

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.

Affected Versions

Any version before v2.12.6 or v2.11.15

Workarounds

None.

Severity
6.4 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/nats-io/nats-server/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.11.15"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/nats-io/nats-server/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.12.0-RC.1"
            },
            {
              "fixed": "2.12.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/nats-io/nats-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33246"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-287",
      "CWE-290"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-24T21:50:25Z",
    "nvd_published_at": "2026-03-25T20:16:33Z",
    "severity": "MODERATE"
  },
  "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 allows hub/spoke topologies using \"leafnode\" connections by other nats-servers.  NATS messages can have headers.\n\n### Problem Description\n\nThe 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.\n\nA 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.\n\nThus NATS clients relying upon the Nats-Request-Info: header could be spoofed.\n\nDoes 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.\n\n### Affected Versions\n\nAny version before v2.12.6 or v2.11.15\n\n### Workarounds\n\nNone.",
  "id": "GHSA-55h8-8g96-x4hj",
  "modified": "2026-03-27T22:10:07Z",
  "published": "2026-03-24T21:50:25Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nats-io/nats-server/security/advisories/GHSA-55h8-8g96-x4hj"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33246"
    },
    {
      "type": "WEB",
      "url": "https://advisories.nats.io/CVE/secnote-2026-08.txt"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/nats-io/nats-server"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "NATS: Leafnode connections allow spoofing of Nats-Request-Info identity headers"
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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