{
  "cveId": "CVE-2026-109855",
  "url": "https://patchblox.com/security/cve/CVE-2026-109855",
  "summary": "CVE-2026-109855 is fixed in node-undici on 1 platform by DEBIAN-CVE-2026-109855 (version 8.12.2\u002Bdfsg\u002B~cs3.2.3-1), released November 1, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "node-undici: undici is an HTTP client library for Node.js",
  "description": "undici is an HTTP client library for Node.js. In versions 8.11.0 and 8.11.1, its experimental WebSocket client, which is enabled by default when HTTP/2 is allowed, mishandles a failed WebSocket handshake over HTTP/2: the request is already marked completed, so the abort becomes a no-op and the underlying HTTP/2 stream is left open with no error listener. When a malicious server then destroys the connection, the orphaned stream emits an unhandled error and the Node.js process exits. A remote, unauthenticated server can therefore crash any client that opens a WebSocket to it over HTTP/2, resulting in a denial of service. The issue is fixed in undici 8.11.2, and users should upgrade to 8.11.2 or later. As a workaround, set allowH2 to false to disable HTTP/2 for WebSocket connections, or avoid opening WebSocket connections to untrusted servers.",
  "published": "2026-10-15T09:17:16Z",
  "severity": "high",
  "cvss": 7.5,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
  "epss": 0.00279,
  "epssPercentile": 0.20468,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "node-undici",
      "release": "Debian 14",
      "fixedVersion": "8.12.2\u002Bdfsg\u002B~cs3.2.3-1",
      "fix": "DEBIAN-CVE-2026-109855",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-109855",
      "released": "2026-11-01T22:29:49Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T19:38:12Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}