CVE-2026-33219 (GCVE-0-2026-33219)
Vulnerability from cvelistv5
Published
2026-03-25 19:55
Modified
2026-03-25 20:10
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Summary
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.
Impacted products
Vendor Product Version
nats-io nats-server Version: < 2.11.15
Version: >= 2.12.0-RC.1, < 2.12.6
Create a notification for this product.
Show details on NVD website


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                "id": "CVE-2026-33219",
                "options": [
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                    "Exploitation": "none"
                  },
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                    "Automatable": "no"
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                    "Technical Impact": "partial"
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                "role": "CISA Coordinator",
                "timestamp": "2026-03-25T20:10:18.603979Z",
                "version": "2.0.3"
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          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
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          "versions": [
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        }
      ],
      "metrics": [
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          "cvssV3_1": {
            "attackComplexity": "LOW",
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            "availabilityImpact": "LOW",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
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      "providerMetadata": {
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      "references": [
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          "tags": [
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          "url": "https://github.com/nats-io/nats-server/security/advisories/GHSA-8r68-gvr4-jh7j"
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          "name": "https://advisories.nats.io/CVE/secnote-2026-02.txt",
          "tags": [
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      "title": "NATS is vulnerable to pre-auth DoS through WebSockets client service"
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    "datePublished": "2026-03-25T19:55:28.363Z",
    "dateReserved": "2026-03-17T23:23:58.314Z",
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    "state": "PUBLISHED"
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  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
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