GHSA-qq8j-7v2v-3rwp

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GHSA-qq8j-7v2v-3rwp

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

Details: ### 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.

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