CVE-2026-19534 (GCVE-0-2026-19534)

Vulnerability from cvelistv5 – Published: 2026-09-04 17:10 – Updated: 2026-09-04 18:18
VLAI
Title
undici vulnerable to Denial of Service via unrequested WebSocket subprotocol
Summary
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 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.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-04 18:18 UTC
CWE
Assigner
openjs CNA under the redhat root
CNA scorecard C 65/100 over 108 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
undici undici Affected: 6.7.0 , < 6.28.1 (semver)
Unaffected: 6.28.1 (semver)
Affected: 7.0.0 , < 7.29.1 (semver)
Unaffected: 7.29.1 (semver)
Affected: 8.0.0 , < 8.10.2 (semver)
Unaffected: 8.10.2 (semver)
guessed Create a notification for this product.
Credits
manus-use mcollina UlisesGascon
Show details on NVD website
To clipboard 

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