GHSA-qq8j-7v2v-3rwp
undici WebSocket client vulnerable to Denial of Service via failed HTTP/2 handshake
At a glance
- Published
- Updated
- CVE
- CVE-2026-109855
- CVSS_V3
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Description
### 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.
Affected packages
| Package | Versions |
|---|---|
| npm · undici | introduced 8.11.0, fixed 8.11.2 |
References
- https://github.com/nodejs/undici/security/advisories/GHSA-qq8j-7v2v-3rwp WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-109855 ADVISORY
- https://github.com/nodejs/undici/pull/5873 WEB
- https://github.com/nodejs/undici/commit/dd28c5c55f4a25f7c441fd4365b1191f96c3b8bf WEB
- https://cna.openjsf.org/security-advisories.html WEB
- https://github.com/nodejs/undici PACKAGE
- https://github.com/nodejs/undici/releases/tag/v8.11.2 WEB
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — GitHub Advisory Database |