undici WebSocket client vulnerable to Denial of Service via failed HTTP/2 handshake

{
  "id": "cf2568199af81c4316483750e6d7134f523e23f31d8510d3d351f1fae1b18a9f",
  "url": "https://osv.dev/vulnerability/GHSA-qq8j-7v2v-3rwp",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "undici WebSocket client vulnerable to Denial of Service via failed HTTP/2 handshake",
    "summary": "### Impact undici's experimental WebSocket client (enabled by default via `allowH2: true`) crashes the Node.js process when it connects to a malicious server over HTTP/2. If the server answers the WebSocket upgrade with a response that fails handshake validation, undici aborts the request, but the abort is a no-op because the request is already marked completed, so the underlying `ClientHttp2Stream` is left open with no error listener. When the server then destroys the connection, the orphaned stream emits an unhandled `error` and the process exits. A remote, unauthenticated server can therefore deny service to any client that opens a WebSocket to it over HTTP/2. undici 8.11.0 and 8.11.1 are affected; the regression was introduced in 8.11.0. ### Patches Upgrade to `8.11.2`. ### Workarounds Set `allowH2: false` to disable HTTP/2 for WebSocket connections, or avoid opening WebSocket connections to untrusted servers, until upgrading.",
    "evidence": "osv:GHSA-qq8j-7v2v-3rwp",
    "products": [
      {
        "name": {
          "value": "undici",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "8.11.2",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-qq8j-7v2v-3rwp",
      "aliases": [
        "CVE-2026-109855",
        "GHSA-qq8j-7v2v-3rwp"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "8.11.0"
                },
                {
                  "fixed": "8.11.2"
                }
              ]
            }
          ],
          "package": {
            "name": "undici",
            "purl": "pkg:npm/undici",
            "ecosystem": "npm"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-qq8j-7v2v-3rwp/GHSA-qq8j-7v2v-3rwp.json"
          }
        }
      ],
      "modified": "2026-10-27T16:15:05.346335461Z",
      "provider": "osv",
      "references": [
        "https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-109855",
        "https://github.com/nodejs/undici/pull/5873",
        "https://github.com/nodejs/undici/commit/dd28c5c55f4a25f7c441fd4365b1191f96c3b8bf",
        "https://cna.openjsf.org/security-advisories.html",
        "https://github.com/nodejs/undici",
        "https://github.com/nodejs/undici/releases/tag/v8.11.2"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-248",
          "CWE-754"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": "2026-10-15T09:17:16Z",
        "github_reviewed_at": "2026-10-27T16:09:45Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-109855",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 462862,
  "published_at": "2026-10-27T16:09:45+00:00"
}