undici's WebSocket client crashes the whole Node.js process during the opening handshake when a server responds with a subprotocol that the client never requested. A default WebSocket connection sends no subprotocol, but if the server's 101…
Exact source revision recorded 25 Oct 2026 05:17:25 UTC. It does not establish the source's current position. Latest evidence.
nvd · CVE-2026-19534
Publishedundici's WebSocket client crashes the whole Node.js process during the opening handshake when a server responds with a subprotocol that the client never requested. A default WebSocket connection sends no subprotocol, but if the server's 101 response includes a Sec-WebSocket-Protocol header, undici dereferences a null value while checking it against the requested list and throws an uncaught TypeError. Because that code runs inside a microtask with no surrounding error handling, the exception propagates and terminates the process under Node's default behavior, instead of gracefully failing the connection as required by the WebSocket protocol. Any application that opens a WebSocket to an attacker-controlled or compromised server, or over a plaintext connection subject to a machine-in-the-middle, can be crashed remotely without authentication in the default configuration. This affects undici versions from 6.7.0 up to 6.28.1, from 7.0.0 up to 7.29.1, and from 8.0.0 up to 8.10.2. Users should upgrade to undici 6.28.1, 7.29.1, or 8.10.2.
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Analyzed
Weakness classifications: CWE-248 · CWE-252
Original publisher date fields
published: 2026-09-04T18:17:51.647
lastModified: 2026-09-16T20:41:08.750
1 source CPE criteria · context only
- cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
The original JSON retains the logical configuration operators, exclusions and version bounds.
- Source published
- 4 Sep 2026 18:17:51 UTC
- Source modified
- 16 Sep 2026 20:41:08 UTC
- Observed here
- 25 Oct 2026 05:17:25 UTC
- Source terms
- NIST NVD usage terms; underlying source attribution retained
Original source record · Cite this exact observation · Complete original publisher JSON
This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.
CVSS 3.1 · ce714d77-add3-4f53-aff5-83d477b104bb · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H