Vulnerability from bitnami_vulndb
Published
2026-03-27 17:45
Modified
2026-03-27 18:14
Summary
NATS is vulnerable to pre-auth DoS through WebSockets client service
Details

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, 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 CVE-2026-27571. That earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable websockets if not required for project deployment.

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Bitnami",
        "name": "nats",
        "purl": "pkg:bitnami/nats"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.11.15"
            },
            {
              "introduced": "2.12.0"
            },
            {
              "fixed": "2.12.6"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "severity": [
        {
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
          "type": "CVSS_V3"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33219"
  ],
  "database_specific": {
    "cpes": [
      "cpe:2.3:a:nats:nats_server:*:*:*:*:*:go:*:*"
    ],
    "severity": "Medium"
  },
  "details": "NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, 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 CVE-2026-27571. That earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable websockets if not required for project deployment.",
  "id": "BIT-nats-2026-33219",
  "modified": "2026-03-27T18:14:10.313Z",
  "published": "2026-03-27T17:45:18.190Z",
  "references": [
    {
      "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": "WEB",
      "url": "https://github.com/advisories/GHSA-qrvq-68c2-7grw"
    },
    {
      "type": "WEB",
      "url": "https://github.com/nats-io/nats-server/security/advisories/GHSA-8r68-gvr4-jh7j"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33219"
    }
  ],
  "schema_version": "1.6.2",
  "summary": "NATS is vulnerable to pre-auth DoS through WebSockets client service"
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.