GHSA-8R68-GVR4-JH7J

Vulnerability from github – Published: 2026-03-24 21:46 – Updated: 2026-03-24 21:46
VLAI?
Summary
NATS is vulnerable to pre-auth DoS through WebSockets client service
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 offers a WebSockets client service, used in deployments where browsers are the NATS clients.

Problem Description

A malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-server before authentication; this requires sending a corresponding amount of data.

This is a milder variant of NATS-advisory-ID 2026-02 (aka CVE-2026-27571; GHSA-qrvq-68c2-7grw). That earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth.

Affected Versions

Any version before v2.12.6 or v2.11.15

Workarounds

Disable websockets if not required for project deployment.

Severity ?
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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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"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33219"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-24T21:46:31Z",
    "nvd_published_at": null,
    "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 offers a WebSockets client service, used in deployments where browsers are the NATS clients.\n\n### Problem Description\n\nA malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-server before authentication; this requires sending a corresponding amount of data.\n\nThis is a milder variant of [NATS-advisory-ID 2026-02](https://advisories.nats.io/CVE/secnote-2026-02.txt) (aka CVE-2026-27571; GHSA-qrvq-68c2-7grw).\nThat earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth.\n\n### Affected Versions\n\nAny version before v2.12.6 or v2.11.15\n\n### Workarounds\n\nDisable websockets if not required for project deployment.",
  "id": "GHSA-8r68-gvr4-jh7j",
  "modified": "2026-03-24T21:46:31Z",
  "published": "2026-03-24T21:46:31Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/nats-io/nats-server/security/advisories/GHSA-8r68-gvr4-jh7j"
    },
    {
      "type": "WEB",
      "url": "https://advisories.nats.io/CVE/secnote-2026-02.txt"
    },
    {
      "type": "WEB",
      "url": "https://advisories.nats.io/CVE/secnote-2026-11.txt"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-qrvq-68c2-7grw"
    },
    {
      "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:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "NATS  is vulnerable to pre-auth DoS through WebSockets client service"
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.