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CVE-2026-109855

7.5 high SSVC exploitation: none Analyzed
NVD · CVE.org

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.

Fix

Patch, vendor advisory and mitigation references on NVD 2

Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.

Change history 4

  1. Cpes+1 CPE criteria (now 1)NVD modified 2026-10-19 20:46
  2. StatusAwaiting Analysis → AnalyzedNVD modified 2026-10-19 20:46
  3. StatusReceived → Awaiting AnalysisNVD modified 2026-10-15 20:38
  4. First seenCVSS 7.5NVD modified 2026-10-15 09:17

Affected (CPE criteria) 1

  • cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*

References 2